The fourth Democratic primary debate in Westerville, Ohio, featured a number of tense exchanges and again highlighted the major policy rifts that continue to divide the field with less than four months to go until the first votes are cast.

While there was relatively little disagreement on the issue continuing to dominate Washington -- the impeachment of President Donald Trump -- the debate, hosted by CNN and The New York Times, featured pitched exchanges on health care, taxes, foreign policy and the candidates' governing philosophies.

Here are five key takeaways from Tuesday night's fourth Democratic debate.

Democrats (mostly) united on impeachment

The Democratic field presented a mostly unified front Tuesday night on the issue of impeachment, with almost every candidate voicing strong support for the House's decision to move forward with the inquiry.

"This is about Donald Trump. But understand, it's about the next president and the next president and the next president and the future of this country. The impeachment must go forward," said Sen. Elizabeth Warren, D-Mass.

"In my judgment, Trump is the most corrupt president in the history of the country," argued Sen. Bernie Sanders, I-Vt.

"They have no choice but to move," former Vice President Joe Biden, who was a consistent skeptic of impeachment before coming out in support of the inquiry last week, said of House Democrats in agreement.

But while the field was united, some lamented that the discussion draws attention away from a robust discussion of the issues that matter most to voters.

"The fact is, Donald Trump -- when we are talking about him -- we are losing," said businessman Andrew Yang. He said he still supports impeachment.

"If impeachment is driven by these hyper-partisan interests, it will only further divide an already terribly divided country," said Rep. Tulsi Gabbard, D-Hawaii, one of the most reluctant supporters of impeachment."

Warren faces the scrutiny of a front-runner, Biden gets support amid attacks

Trump may have been the target of the most ire from the Democratic field Tuesday night, but Warren was likely a close second.

On health care, taxes and jobs, Warren fended off a spate of attacks from more moderate candidates like South Bend, Indiana, Mayor Pete Buttigieg and Minnesota Sen. Amy Klobuchar.

Even former Texas Rep. Beto O'Rourke went after Warren, labeling her as "punitive" against certain segments of the American public.

"I'm really shocked at the notion that anyone thinks I'm punitive. Look, I don't have a beef with billionaires. My problem is, you made a fortune in America, you had a great idea, you got out there and worked for it, good for you, but you built that fortune in America, I guarantee you built it in part using workers all of us helped pay to educate," Warren said, defending her plan to institute a wealth tax.

"You are making Republican talking points right now in this room by coming out for a plan that's going to do that," Klobuchar said of Warren's support for Medicare for All, a plan the Minnesotan says will kick nearly 150 million people off their health insurance plans.

Along with her consistent rise in both national and early state polls, Warren is expected to face increased scrutiny on both her record and slate of ambitious policy goals. Tuesday night may mark the beginning of that phenomenon.

Biden, who came into the debate as a central figure in the impeachment probe, was spared any attacks from his Democratic rivals and in fact got a boost of support from Sen. Cory Booker, D-N.J., who said any attacks only benefit Trump.

"We are literally using Donald Trump's lies and the second issue we cover on this stage is elevating a lie and attacking a statesman. That was so offensive ... the only person sitting at home that was enjoying that was Donald Trump," Booker said.

Democrats rumble on health care again

The divide between progressive and moderate Democratic candidates was on full display early at Tuesday's debate, when leading progressive candidates Warren and Sanders took on a barrage of questions from more moderate rivals over their push for a "Medicare for All" overhaul of the American health care system.

Warren, specifically, was peppered with questions from moderates and declined to answer questions over her continued reluctance to detail how she'll pay for her Medicare for All plan and whether or not taxes will be raised on the middle class -- an issue Buttiegeg raised in a heated moment early in the debate.

"Well, we heard it tonight. A yes or no question that didn't get a yes or no answer," Buttiegeg said, taking on Warren. "Your signature, senator, is to have a plan for everything, except this."

Warren fired back, taking a shot at the mayor's own health care plan.

"Whenever someone hears the term 'Medicare For All Who Want It,' understand what that really means. It's Medicare For All who can afford it."

Sanders, the author of the Medicare for All bill Warren and other senators on the debate stage supported, also jumped in to defend his bill, arguing, "Well, as somebody who wrote the damn bill, as I said, let's be clear: Under the Medicare For All bill that I wrote, premiums are gone. Co-payments are gone. Deductibles are gone. All out-of-pocket expenses are gone. We're going to do better than the Canadians do."

And as Warren continued to dodge questions regarding how she plans to specifically pay for her health care plan, moderate candidate Klobuchar, also took a shot at the progressive stalwart.

"At least Bernie's being honest here and saying how he's gonna pay for this and that taxes are going to go up," Klobuchar said. "And I'm sorry Elizabeth, but you've not said that, and I think we owe it to the American people to tell them where we're gonna send the invoice."

Mayor Pete comes out swinging

The South Bend, Indiana, mayor has begun to shed his non-confrontational style in recent weeks, and Tuesday night he continued that aggressive strategy.

Buttigieg confronted Warren early over her health care plan, and later had one of the most intense showdowns of the night with O'Rourke over their gun control policies.

"I don't need lessons from you on courage -- political or personal," Buttigieg snapped in response to O'Rourke, after the former Texas congressman accused him of listening to "the polls and the consultants and the focus groups."

While he has maintained his position near the top of the pack in fundraising and secured his spot on the next debate stage in November, Buttigieg has struggled to join the ranks of Biden, Warren and Sanders at the top of most public polls.

Tuesday also afforded Buttigieg an opportunity to elevate his voice in the foreign policy arena amid Trump's controversial decision to remove U.S. troops from northern Syria.

He sparred with Gabbard, the only other veteran on the stage, who he said was "dead wrong" that the U.S. needs to withdraw from the area and accused Trump of degrading U.S. leadership on the global stage.

"This president has betrayed American values; our credibility has been tattered. I will restore U.S. credibility before it is finally too late," Buttigieg said.

Sanders rebounds after heart attack

Two weeks after suffering a heart attack and having two stents placed in a blocked coronary artery -- and with questions swirling around his campaign's future -- Sanders rebounded at Tuesday night's debate, delivering a lively and boisterous performance that his supporters have known to expect from the progressive leader.

Sanders was lively, pointed and -- at times -- even jovial, joking with candidates on the stage.

And in one big moment, the Vermont senator amid a flurry of attacks from more moderate rivals, railed in quintessential Sanders' fashion, offering a resounding and passionate defense of his plan to completely rethink the American health care system through a Medicare for All plan.

"The issue is whether the Democratic party has the guts to stand up to the health care industry which made $100 billion in profit. Whether we have the guts to stand up to the corrupt price fixing pharmaceutical industry, which is charging us the highest prices in the world for prescription drugs," Sanders said, raising his voice. "And if we don't have the guts to do that, if all we can do is take their money, we should be ashamed of ourselves."

Later in the debate, Sanders -- who would be the oldest person to hold the office in history -- was asked about his health and emphatically, again, reiterated that he's ready to carry on, even teasing his upcoming New York City rally this weekend.

"We're going to have a special guest at that event, and we are going to be mounting a vigorous campaign all over this country," Sanders said, before thanking people across the country for supporting him amid the health scare. "I just want to thank you from the bottom of my heart, and I'm so happy to be back here with you this evening," He added, in a touching moment for a candidate so often reluctant to talk about his personal life.