(CNN) CNN Opinion asked commentators to weigh in on the Democratic debate -- and what it may mean for the primary ahead. The views expressed in this commentary are their own.

Nayyera Haq: Biden shows he can evolve

The challenge with having two septuagenarian, long-term senators on the debate stage is that serious discussion of the big issues facing the country so easily devolve into tirades about decades-old votes and political squabbles. Bernie Sanders reminded all of us that his once radical ideas have now become mainstream parts of the political conversation. But it was Joe Biden, "coming around now," on his adoption of Senator Elizabeth Warren's bankruptcy proposals, his rejection of the Hyde Amendment and his adoption of free public college for families earning less than $125,000, who showed that he is capable of listening and evolving.

When a moderator asked for a commitment to having a woman as vice president on the ticket, the candidates' relative ability to adapt in response to feedback was clearly on display. Biden's answer was an unequivocal yes, followed by a commitment to appointing a black woman to the Supreme Court. Biden used the debate platform to make a first-time declaration aimed at assuaging the female voters who have been disheartened by seeing the debate stage narrow from five female candidates to zero, while also acknowledging that black women are the backbone of the Democratic party.

Whether it was a calculated declaration does not change the fact Biden is committed, which stands in sharp contrast to Sanders' answer: "In all likelihood, I will...for me, it's not just nominating a woman, it's making sure we have a progressive woman."

At a time when many Americans are panicked about the present, moving out of debating policies of the 1990s was critical for both candidates. Sure, Sanders proved that he was the purer, more progressive candidate -- we knew that. Biden consistently stayed focused on the future, with plans he would enact and what he would do differently than Trump. If Biden continues to look forward and embrace ideas from the left, he will show voters that he can do what he has talked about all along -- be the consensus candidate that brings Democrats to the White House in 2020.

Nayyera Haq is a host on SiriusXM Progress and CEO of an international communications firm. She served in the Obama administration as a senior adviser in the State Department and a senior director in the White House. Follow her on Twitter @nayyeroar

Raul Reyes: A welcome discussion of immigration

Raul A. Reyes

The good news from Sunday night's debate is that both Joe Biden and Bernie Sanders delivered spirited presentations of their ideas, and each gave a preview of how he might take on President Donald Trump. Biden needed to demonstrate that he can be effective in a one-on-one debate. Sanders needed to contrast his progressive ideas with that of his rival. Done and done. Democrats can take heart: Biden had his strongest debate performance to date, while Sanders showed that he is not about to cede the nomination without a fight.

At its best, this debate showed both candidates' strength on issues like the coronavirus crisis and immigration. Biden asserted that any person who needed testing or treatment for the coronavirus "would be held harmless," regardless of immigration status, adding that women who are the victims of domestic violence should not be deported. He also committed to a moratorium on deportations (except for felons) for the first 100 days of his administration.

Sanders noted that undocumented people would be covered by his Medicare for All proposal, and that he intends to stop ICE raids. This immigration discussion was good, as the topic has not been substantively discussed in the last few debates -- and the eventual nominee will face a president who has made immigration his signature issue. Kudos to both candidates for defending the legal right of asylum-seekers to seek humanitarian relief at the border.

At other points, this debate devolved into unproductive bickering. Right now, the public is anxious, and the back-and-forth sniping was not a presidential look for either candidate. Biden said it best when he declared, about he and Sanders, that "we don't disagree on principles."

The lack of a live audience turned out to be a plus, as it left more time for the debate itself, and the candidates could not rely on applause lines. It was also a highlight to see Ilia Calderon, who is Afro-Latina, as a moderator -- an important reflection of the diversity of the Latino community.

Raul A. Reyes is an attorney and a member of the USA Today board of contributors. Follow him on Twitter @RaulAReyes

Frida Ghitis: Biden makes big news on his running mate

Frida Ghitis

For once, the loser by a mile in the Democratic debate was Donald Trump. Former Vice President Joe Biden and Senator Bernie Sanders offered presentations that were more reasonable, coherent and factual than anything the President has managed while reading a speech from the teleprompter or speaking from the podium. The contrast with a president floundering in a national emergency was striking.

If Trump was the loser, the clear winner was Biden. The former Vice President made news, announcing he will choose a woman as his vice-presidential running mate (clear your calendars Kamala Harris and Amy Klobuchar).

Gone is the Biden who seemed lost on a crowded debate stage. This debater was crisp, calm and cogent through the entire two hours. As the hours passed, he never lost his focus and remained totally articulate. He should be careful; he might lose the benefit of low expectations.

Biden made few major gaffes -- except perhaps for parts of his China answer, but that may have been calculated. He looked confident and relaxed. If his body language was planned, it worked. His quarter-turn toward Sanders, with one hand in his pocket, made him look both in command and approachable.

While Biden came across as profoundly compassionate and pragmatic, Sanders, who has been consistently strong in articulating what is wrong with America, remained hyper-focused on his ideological, revolutionary position. Sanders did himself no favors by refusing to agree with Biden's suggestion that the two Democrats share similar goals diametrically opposed to Trump's ("details make a difference," Sanders said); refusing to fully commit to choosing a woman running-mate ("My strong tendency is to move in that direction") and initially seeming dismissive of the Paris Climate Accord ("Who cares").

With the country facing a huge challenge, and the current President leading a dangerously chaotic response, one can only wonder why Democrats don't move on to unify the party without delay. This should be the last debate. That would be the biggest loss for Trump.

Frida Ghitis, a former CNN producer and correspondent, is a world affairs columnist. She is a frequent opinion contributor to CNN, a contributing columnist to the Washington Post and a columnist for World Politics Review. Follow her on Twitter @fridaghitis

Van Jones: Democrats need a dose of Biden and Sanders to win in November

Van Jones

Neither wing of the Democratic Party got what they wanted tonight: neither a knock-out blow for Vice President Joe Biden, nor a comeback shot for Sen. Bernie Sanders. But both were well-represented.

On issue after issue, Sanders made it clear he understands the depth of America's need for big solutions. He noted that the seeds of today's COVID-19 response failure were planted in a broken healthcare system years ago. He showed that the progressive agenda can help Americans who are barely holding on when work no longer pays. He pressed Biden on the flaws in his record. And the exchange on climate showed how Sanders -- along with New York Rep. Alexandria Ocasio-Cortez and the Sunshine Movement -- finally forced our nation's leaders to think big about facing the existential threat of the climate crisis.

In moment after moment, Biden made it clear he understands the depth of America's need for hope and normalcy. He passed up a debate over the politics of Medicare for All to talk about uniting the country around an urgent plan to stem the threat of coronavirus. He spoke to millions of too-long-overlooked women -- and women of color -- when he promised to pick a female running mate. This follows the former Vice President vowing to choose an African-American woman for the Supreme Court. And Biden went further on climate than many Democrats were willing to go just a few years ago -- during the Obama administration.

The first 15 minutes on coronavirus might have been the most important of the debate. Biden was empathetic and unifying. Sanders was unflinching in his diagnosis of the deep problems and the big solutions. Both represented themselves well. Democrats will need some of both to beat Trump in November.

Jen Psaki: Biden's handling of a crisis sounded presidential

Jen Psaki

Former Vice President Joe Biden and Senator Bernie Sanders knew that the focus of tonight's debate would be on the crisis that is dominating not just the United States, but the global community.

Both were significantly more clear, coherent and thoughtful than the current President of the United States. But their approaches were different.

Biden focused on his experience and ability to address this crisis right now.

Sanders focused more on how his ideology would help address what happens after coronavirus.

Both are important. I have no doubt Joe Biden knows exactly what to do during a crisis. He lived through eight years of them in the White House, including health crises.

And I have no doubt that Bernie Sanders would continue to be a voice for the millions of people who are worried about what happens when the crisis is over.

But at a time when families are worried about whether grandparents are safe, kids are asking hard questions to answer about why they can't hug their friends, and President Trump continues to mislead and scare the public, Joe Biden's focus on what he would do about the crisis right now was a smart reminder of what a real President sounds like.

Jen Psaki, a CNN political commentator, was the White House communications director and State Department spokeswoman during the Obama administration. She is vice president of communications and strategy at the Carnegie Endowment for International Peace . Follow her at @jrpsaki

Peter Bergen: Biden focused on the here and now of the coronavirus crisis

Peter Bergen

Obviously, the question of who might better handle the coronavirus crisis was front and center in the debate between former Vice President Joe Biden and Sen. Bernie Sanders.

Sanders rightly said it was time for President Donald Trump to stop "blabbering" about the coronavirus and confusing the general public. Indeed, Trump has made multiple misleading statements about the crisis, not least just hours before Sunday's debate when he said that the US government had "tremendous control" of the virus. This is, of course, patently not the case.

During the debate, Biden returned often to his role in mitigating the Ebola crisis in 2014, which doesn't seem that relevant since Ebola posed nothing like the scale of the threat that the US faces with coronavirus. Biden also deployed the bromide that he would assemble experts in the Situation Room at the White House to deal with the crisis, which is a lot like saying "we will study the problem."

But overall Biden did better on the question about what to actually do now about the coronavirus. When CNN's Dana Bash asked Biden if he would call in the US military to help, Biden was clear that had would indeed do so to build additional hospitals, which could well be necessary, given that hospitals may be overwhelmed as the crisis deepens.

Sanders ducked the same question, instead concentrating on his Medicare for All proposal, which is all fine and good but is not the kind of policy proposal that will help with the immediate crisis.

Biden also called for immediate testing for the coronavirus among vulnerable seniors in nursing homes. Again, this is the kind of practical proposal that is needed right now as the crisis deepens.

Peter Bergen is CNN's national security analyst, a vice president at New America, a professor of practice at Arizona State University. His new book is " Trump and His Generals: The Cost of Chaos ."

Alice Stewart: Substance and style in the midst of coronavirus

Alice Stewart

With former Vice President Joe Biden and Vermont Sen. Bernie Sanders facing off in the Democratic primary debate, it was the coronavirus pandemic that took center stage. There were two key takeaways for those tuning in: what the candidates had to say about the national emergency, and how they said it.

Biden laid out his plan for taking care of those exposed to the virus and providing more access to testing for all.

Sanders avoided details of a response plan, opting instead to voice his desire to "shut this president up right now." As expected, Sanders also used the coronavirus outbreak as an example of why his Medicare for All plan is necessary.

In contrast, Biden was effective in making the case that Medicare for All is the wrong way to address health care in general, and it "would not solve the problem at all" when it came to COVID-19.

Biden carried a different tone, full of empathy, and acknowledging the serious times we are facing. Sanders' delivery was similar to past debates -- pushing progressive policies and insulting President Donald Trump.

It was a strong debate for Biden -- not only because of what he said, but also because of how he said it.

Alice Stewart is a CNN political commentator, resident fellow at Harvard University's Kennedy Institute of Politics, and former communications director for Ted Cruz for President.

Julian Zelizer: The divide between parties has never been clearer

Julian Zelizer

The contrast between parties was apparent right off the bat. Whereas President Trump has spent much of his time amid the coronavirus crisis speaking about how great things are, or spreading disinformation, both former Vice President Joe Biden and Vermont Senator Bernie Sanders took a very different path. They expressed their empathy for those who have suffered from the virus, talked about real and immediate policy needs—such as widespread testing—and spoke about the economic fears of working Americans.

Although many issues divide these candidates, together they displayed a fundamental difference on where the parties stand in 2020. Democrats remain concerned with governance, value expertise, and focus their attention on how public policy can help the lives of Americans. Republicans are operating in a Trumpian world of disinformation where institutions are not taken seriously and the work of running a government is no longer a priority.

The severity of the crisis that the United States now faces has elevated—in ways we could not have imagined — the political value of a party that stands for these principles.

Biden's commanding lead and his solid debate performance tonight in his first one-on-one debate will greatly benefit his larger campaign. The value of his experience in the White House has greatly increased in value since the last time the Democrats met on the debate stage.

The image of the party, as well as his leadership style, makes him stronger than at any point in this race. Americans are watching this debate as their cities and towns close down. Biden's ability to simply govern and run a stable White House will now seem to move voters as much as the ideas that Sanders offers.

Sarah Isgur: Democrats are experiencing déjà vu

Sarah Isgur

With the first half hour of the debate focused entirely on the public health crisis facing the country, Sanders' traditional economic populism message never found a solid footing. Instead, in an unusually uneven performance, he struggled and stumbled to answer questions about how he would respond to the current crisis, including whether he would deploy the military and how he would respond to China's initial suppression of information related to the coronavirus outbreak.

But 45 minutes in, Sanders hit his stride in one area -- direct and sustained attacks on the frontrunner Joe Biden, challenging the Vice President on taking money from Super PACS, as well as voting for the bank bailout and the Iraq War.

For Democrats, this may feel like déjà vu all over again.

Following a string of disappointing primary results -- and with more losses on the horizon in states like Florida and Arizona this Tuesday -- Sanders is facing the reality that it is becoming a near mathematical impossibility for him to receive enough delegates to secure the nomination. This has caused many leaders in the Democratic Party to raise concerns that Sanders' continued presence in the race could inflict lasting damage on Biden heading into the general election.

The concern isn't a new one. In an interview after her 2016 loss, Hillary Clinton said Sanders' continued attacks on her "caused lasting damage, making it harder to unify progressives in the general election and paving the way for Trump's 'Crooked Hillary' campaign." That year, millions of voters for Barack Obama in 2012 either voted for Donald Trump or stayed home.

The Democratic Party's first priority is to beat Trump in November. But Sanders' attacks on Biden tonight may have been a little too reminiscent of 2016 for those who want to win back the White House.

Sarah Isgur is a CNN political analyst. She has worked on three Republican presidential campaigns and is an adjunct professor at George Washington University's School of Media and Public Affairs. She is a graduate of Harvard Law School.

Scott Jennings: The two didn't exactly cover themselves in glory

Scott Jennings

I was surprised that the two candidates didn't walk out and at least have some prepared show of collegiality or unity. No, this debate opened and unfolded like this: Joe Biden wanted to knock out Bernie Sanders once and for all, and Bernie Sanders was not having it and very much believed he was still alive and viable for the nomination.

I assumed Biden would just pretend he's the nominee and largely ignore and/or pat Sanders on the head, but he did not, instead repeatedly denigrating Sanders' signature health care plan: Medicare for All. By the end of the first hour, they were arguing about the size of their donations and how many Super PAC's they dealt with, about which no American gives a flying flip as they prepare to face their new coronavirus realities.

Hard to know what to make of the first hour: Biden, prone to misspeaking and bungling lines, had a bizarre few seconds when he mixed up coronavirus and swine flu, then called the swine flu "N1H15," and then apparently forgot the word "Ebola" by referring to "what happened in Africa," a moment the Trump campaign was all too happy to amplify. Sanders then went off for a few seconds referring to coronavirus as "Ebola," appearing hung up on the term.

I assume that because Biden is better at platitudes and pablum, he'll be judged the winner, while Sanders will be judged to have failed to move beyond the issues that motivate his base -- but not the broader Democratic electorate. Honestly, though, I am not sure either covered themselves in glory as this two-man debate kicked off. Sanders landed the toughest blows with his challenge about whether Biden had once talked about the need to cut Social Security and Medicare -- an exchange I bet the Democratic National Committee wish hadn't happened.

Scott Jennings, a CNN contributor, is a former special assistant to President George W. Bush and a former campaign adviser to Sen. Mitch McConnell. He is a partner at RunSwitch Public Relations in Louisville, Kentucky. Follow him on Twitter @ScottJenningsKY

SE Cupp: Biden and Sanders should stick to criticizing Trump

SE Cupp

When Bernie Sanders and Joe Biden were focused on Donald Trump's lack of leadership and the urgency of now, they both shined. When they descended into squabbles over old votes -- whether it was Biden's Iraq War vote or Sanders' gun votes -- they both looked small and really out of touch.

They need to understand and quickly adapt to the fact that there are new rules -- the ground underneath them has changed. The pandemic and resulting fear and chaos mean they need to pick new fights and leave the old ones behind.

Whatever plans they had to take each other and Trump on should be discarded for campaigns centered around the need for a calm and steady hand, experience, a commitment to expertise, transparency, truth and strength. Voters are laser-focused on Trump's ability to guide them through this unprecedented health crisis, and whatever Sanders or Biden are talking about should keep that top of mind.

SE Cupp is a CNN political commentator and the host of " SE Cupp Unfiltered ."

Aaron David Miller: Why Biden won the debate

Aaron David Miller

Tonight's debate reflected the different realities confronting the Biden and Sanders campaign. Vice President Joe Biden -- whose campaign is surging -- knew exactly what he wanted to do: act presidential. The other, Bernie Sanders -- whose campaign is in jeopardy and who may well drop out of the campaign soon -- didn't and it showed. Winner? Joe Biden.

Who looked presidential? The debate was essentially won in the first 25 minutes during their discussion of the key issue on Americans' mind tonight -- coronavirus. Biden sounded and acted like a president -- "we're at war with a virus." Sanders' responses sounded like those of a policy wonk -- a wash, rinse and repeat of his commitment to Medicare for All, untethered from the national crisis we face now.

Demeanor: Biden was as articulate and fluent as he's been in any of these debates, looking stunningly comfortable with few glitches and goofs. In contrast, Sanders too often seemed annoyed, irritated and, at times, angry.

Moving Biden to the left: If Sanders' objective was to try to move Biden to the left on key issues such as income equality, taking money from big corporations, climate change and health care, he failed. Meanwhile, Biden may have missed a few opportunities in reaching out to Sanders supporters on an issue such as climate change.

Democratic unity: Committed to unifying the Democratic Party to beat Trump, there wasn't much of an effort on either man's part to do that tonight. There was a good deal of hot debate and mutual attacks likely to push supporters of Sanders and Biden farther apart. It's very much an open question whether Sanders' supporters won't come around easily and could stay home instead of voting.

Aaron David Miller is a senior fellow at the Carnegie Endowment for International Peace and author of " The End of Greatness: Why America Can't Have (and Doesn't Want) Another Great President ." Miller was a State Department Middle East analyst negotiator in Democratic and Republican administrations.

Charlie Dent: Solutions or revolution?

Charlie Dent

In the midst of the coronavirus pandemic, the candidates at Sunday night's debate presented a clear contrast, more in style than substance -- with Joe Biden speaking in reassuring terms, while Bernie Sanders ranted on themes we have heard from him for decades.

Sanders absurdly used the immediate COVID-19 crisis to advocate for Medicare for All and a single payer system as a solution. Biden called Sanders out by pointing to Italy's single payer system and its irrelevance to their country's inadequate response. Further, the former Vice President offered specific policy responses to the immediate crisis, while Sanders kept touting Medicare for All and warning about "profiteering" pharmaceutical companies. He called the very companies we are demanding to develop lifesaving diagnostics and vaccines "crooks." Americans today want reassurance and stability -- an advantage for Biden.

Viewers were also treated to the usual Sanders bromides on big banks and big oil. The far left's war with industrial and agricultural America that contributed to Trump's 2016 victory never ends in Sanders' world.

Biden appeared to drift at times toward positions held by Sanders. Caution to Biden: Millions of hard-working Americans pay their bills and repaid their student loans. Promising any form of free college will not endear them. "No new fracking" may placate the far left but is not a winning message in Biden's hometown of Scranton or western Pennsylvania.

Overall, Sanders attacked aggressively. He focused more on the past than the future. Biden came off as more presidential and spoke directly to the current emergency. Nothing tonight changed the trajectory of Biden's impending nomination. The only remaining question is when and how Sanders recognizes reality and bows out.

Republican Charlie Dent is a former US congressman from Pennsylvania who served as chairman of the House Ethics Committee from 2015 until 2016 and chairman of the House Appropriations Subcommittee on Military Construction, Veterans Affairs and Related Agencies from 2015 until 2018. He is a CNN political commentator.