(CNN) The mass shootings in Texas and Ohio have turned the 2020 presidential campaign into an increasingly visceral referendum on the nature of Donald Trump's presidency and the message that delivered him to the White House.

In speeches , statements and interviews over the past 72 hours, the Democrats running to replace Trump have -- in the most direct terms yet -- sought to confront the racial animus fueling his politics, while attacking the President over his pandering to white supremacists. It's a stark difference from one week ago when talk on the campaign trail was dominated by reaction to a contentious Democratic primary debate.

The strategies and tactics adopted by the candidates have provided new insight and clues into how they would govern if elected, and the ways -- over the coming months -- they will seek to defeat not only Trump, but the principles underlying Trumpism. Their reactions have also signaled an a new willingness to draw a straight line between the President's words and racist violence.

Biden and Booker lash Trump in speeches

Former Vice President Joe Biden and New Jersey Sen. Cory Booker laced their calls for unity on Wednesday with lacerating attacks on Trump in specially scheduled speeches, Biden's in Iowa and Booker from the Emanuel AME Church in downtown Charleston, South Carolina, where nine black parishioners were killed by a white supremacist gunman in 2015.

From the beginning of his campaign, Biden has cast the 2020 election as a "battle for the soul of this nation." But in the video announcing his candidacy, and in subsequent talks, he also suggested that Americans might look back at a one-term Trump presidency as "an aberrant moment in time."

Biden's words on Wednesday in Iowa suggested he is moving toward a more historically complete message -- reminiscent of the view that has been advocated most often by more progressive candidates, like Sens. Bernie Sanders and Elizabeth Warren.

"I wish I could say that this all began with Donald Trump and will end with him. But it didn't -- and I won't," Biden said. "American history is not a fairytale. The battle for the soul of this nation has been a constant push-and-pull for 243 years between the American ideal, that says we're all created equal, and the harsh reality that racism has long torn us apart."

The former vice president also offered a taunting dismissal of Trump's recent, scripted remarks condemning the violence in Texas and Ohio.

"In both clear language and in code, this President has fanned the flames of white supremacy in this nation," Biden said, before baiting Trump -- successfully -- by describing the comments as a "low-energy, vacant-eyed mouthing of the words written for him."

Trump, who was traveling between stops in the Ohio and Texas during Biden's speech, obviously caught wind of Biden's remarks and responded on Twitter.

"Watching Sleepy Joe Biden making a speech. Sooo Boring!," he wrote , before suggesting a Biden presidency would please the Chinese government. Before setting out on his trip, Trump outside the White House drew an equivalence between white supremacist and antifascist groups.

"I have concerns about the rise of any group of hate," Trump said. "Whether it's white supremacy, whether it's any other kind of supremacy, whether it's Antifa, whether it's any group of hate I'm very concerned about it and I'll do something about it."

Hours before Biden's speech and almost a thousand miles away, Booker in South Carolina also cast the violence of the past days in a more sweeping context. Like Biden would, the New Jersey senator referenced the similarities between the language used by Trump to describe immigration and immigrants and the words found in the manifesto of the alleged Texas killer.

"The act of anti-Latino, anti-immigrant hatred we witnessed this past weekend did not start with the hand that pulled the trigger," Booker said. "It did not begin when a single white supremacist got into his car to travel 10 hours to kill as many human beings as he could."

Though he did not address Trump by name, Booker accused the President and his allies of emboldening racists and inciting the El Paso attack.

The alleged killer's dark fervor, he said, had been "planted in fertile soil, because the contradictions that have shadowed this country since its founding remain a part of our body politic. It was sowed by those who spoke the same words the El Paso murderer did: warning of an 'invasion.' It was sowed by those who spoke of an 'infestation,' and 'disgusting cities,' 'rats and rodents,' talking about majority-minority communities."

O'Rourke stays at home to fight

While Booker and Biden purposed their remarks to specifically address the recent violence, former Texas Rep. Beto O'Rourke, an El Paso native whose life and campaign is still based in the city, has clung tight to his frightened community, effectively leaving the stump to lead the way back home.

O'Rourke, whose 2018 Senate campaign became a national cause for Democrats following his viral defense of activist professional athletes, has spoken over the past few days with a moral vigor and clarity that seemed to have eluded him during a stagnant to-date presidential bid.

Asked by a reporter after a Sunday in El Paso if there was anything Trump could do "to make this any better," O'Rourke -- emotional after a vigil for the victims and their families -- shot back in frustration.

"What do you think? You know the s--t he's been saying. He's been calling Mexican immigrants rapists and criminals. I don't know, like, members of the press, what the f--k?," he said. "You know, I -- it's these questions that you know the answers to. I mean, connect the dots about what he's been doing in this country. He's not tolerating racism, he's promoting racism. He's not tolerating violence, he's inciting racism and violence in this country."

O'Rourke's profanity might have drawn the initial attention, but his message to the public echoed the indignation of voters who argue that the time for speculating over or trying to predict Trump's behavior -- when it has become so plain to see -- should be over.

The Texan will not go to Iowa this weekend, as previously planned, and has not yet decided when he will return to the campaign trail. But like the other candidates, he has been firm in connecting the President's words to the bloody attack launched against his city.

"(Trump) is trying to intimidate this community, to make us afraid of the border, of immigrants," O'Rourke told reporters in El Paso on Wednesday morning.

Like Biden, O'Rourke during a morning memorial at El Dorado High School, looked back to the founding of the country -- pointing to its aspirations and how, despite great strides, "we have never fully lived up to that promise" -- before turning to a defense of El Paso and similar places.

"We are one of the safest cities, if not the safest, cities in the United States of America," O'Rourke said. "We must remind ourselves and tell the rest of the country that we are safe not despite the fact that we are city of immigrants and asylum-seekers and refugees, people who came from the planet over to find a home here in El Paso, Texas, but that very fact is what makes us strong and successful and safe and secure in the first place."

Later on, as Trump made his way from Dayton, Ohio, where he visited shooting victims in the hospital, to El Paso, O'Rourke joined protests against the presidential visit, which local leaders like Rep. Veronica Escobar had advised against . In Trump's last appearance in the city, for a political rally, a supporter attacked a BBC reporter and the President spread misleading claims about the city's safety.

After speaking at a demonstration, O'Rourke told CNN he planned to attend victims' funerals and make a trip to Ciudad Juárez, Mexico, where seven of the 22 victims lived, before continuing on with his national campaign. Later on, he gave a young, tearful man who said he was at the Walmart during the shooting his personal phone number, and a promise to help him in any way he could.

A week after fierce debates, Dems unite

Only a couple weeks ago, Booker and Biden were engaged in a heated debate over the former vice president's record on race. And during the debates last week in Detroit, Democrats were at one another's throats, sometimes warning the country that their rivals were unelectable, while sparring over health care, foreign policy and, in the case of immigration, former President Barack Obama's record.

But those arguments have largely evaporated from sight since the Saturday shooting in El Paso. Trump, who has mostly stuck to his inflammatory rhetoric on Twitter, did for the Democrats what he could not for the country: inspired solidarity.

Candidates other than Biden, Booker and O'Rourke have mostly kept to their previous commitments, while flooding television and social media with increasingly pointed denunciations of Trump and notes of solidarity with the victims -- and one another. California Sen. Kamala Harris' campaign bought lunch for the O'Rourke staff in El Paso and Harris spokesman Ian Sams told CNN the campaign has raised nearly $100,000 for gun violence prevention organizations since the shootings.

They also roundly condemned the White House over a CNN report, published Wednesday afternoon, that the White House had rebuffed a push by the Department of Homeland Security to prioritize domestic terror threats, like those posed by white supremacists.

"Homeland Security officials battled the White House for more than a year to get them to focus more on domestic terrorism," one senior source close to the Trump administration told CNN. "The White House wanted to focus only on the jihadist threat which, while serious, ignored the reality that racial supremacist violence was rising fast here at home. They had major ideological blinders on."

Harris linked to the story on Twitter and said , "People are getting killed, and this President is turning a blind eye to America's national security threats."

The former prosecutor has, in the aftermath of the shootings, repeated her promise to use the power of the presidency to implement strict new gun control measures within the first few months of her term.

"Whether at a festival, place of worship, school, movie theater, or Walmart, you should always be able to feel safe," Harris tweeted. "As president, I'll give Congress 100 days to send gun safety legislation to my desk. If they refuse to act, I'll take executive action to protect our communities."

The killings in El Paso have also brought added attention to former Housing and Urban Development secretary Julián Castro, the only Latino in the primary.

Speaking to NBC, Castro underscored the heightened intensity of the campaign and painted a stark image of Trump's political maneuvering.

"For a President now to base his entire political strategy on turning the Latino community, and especially recent immigrants, into 'the other,' into the danger toward America -- it doesn't belong in this country, he doesn't belong as President," Castro said . "And that's one of the reasons I know that I'm running to replace him and I bet that a lot of other people who are in this race feel the same way."

Outside of Texas, the gravity of the El Paso killings has emboldened Democrats to be more direct, and in the case of Sanders, more personal in how they describe their reasons for running.

Sanders, who has repeatedly denounced Trump as a "racist" and "xenophobe" on the campaign trail this year, also kept to his planned campaign stops -- though he, like others, will now attend a forum on gun control in Iowa this weekend. But in a Medium post on Sunday, he took the unusual step of tying the current situation to his own, painful family history.

"I am personally all too familiar with the barbarity that comes from hateful ideology," Sanders wrote. "Most of my own father's family was brutally murdered at the hands of Hitler's white supremacist regime. That regime came to power on a wave of violence and hatred against racial and religious minorities. We cannot allow that cancer to grow here."

His fellow progressive, Warren, issued a similar warning against what the campaigns have almost uniformly described now as a wave of hate drawing strength underfoot from the White House.

"White supremacy is a domestic terrorism threat in the same way that foreign terrorism threatens our people. And it is the responsibility of the President of the United States to help fight back against that," Warren told CNN. "Not to wink and nod and smile at it and let it get stronger in this country."