Warren joins 'The View' decrying Trump's actions abroad and at home

"Having killed Soleimani does not make America safer," she told the hosts.

Sen. Elizabeth Warren of Massachusetts joined ABC’s “The View” Tuesday, her second guest appearance as a presidential candidate.

The appearance comes as impeachment looms over both the Senate and the 2020 presidential campaign trail -- and as the strike on Maj. Gen. Qassem Soleimani, the head of Iran's elite Quds Force, has stirred a marked inflection point for primary candidates now auditioning for the role of commander-in-chief.

"Having killed Soleimani does not make America safer," she told the hosts, continuing an ongoing critique of President Donald Trump's approach to foreign policy. "He has moved us close to the edge of war."

“This is the time not only that we need to stand up," she said. "We need to stand up and be loud."

She was pushed by The View co-host, Meghan McCain, on her switch in rhetoric. Over the weekend, Warren drew heat for focusing on Soleimani, vilifying him as a “murderer” rather than railing against escalation in the Middle East of any kind, as Vermont Sen. Bernie Sanders has done.

Progressive supporters backing Warren were uncomfortable with her initial response, upset with its centrist thrust and dearth of the “big, bold, structural” stances that won them to her side, multiple sources told ABC News. By the next day, her rhetoric showed a clear U-turn: calling the strike an “assassination,” as Sanders had already done.

Warren made rare Sunday show appearances over the weekend -- her first as a presidential candidate, in fact -- and continued to attack and criticize President Trump without mentioning Soleimani.

“I don’t understand the flip flop," McCain said.

“This isn’t a change — the question is what response the president should make," Warren responded as she affirmed that Soleimani was part of a group that’s been designated as a terrorist.

She also weighed in on John Bolton, Trump’s former national security adviser, who now says he’s willing to testify before the Senate – a move that changes the political calculus in what’s become a game of chicken between Democrats and Republicans on a pending impeachment trial and emerging as the first potential wild-card in the upcoming proceedings.

“Now's the time to step up, Mitch Mcconnell, and lay out what the rules are gonna be,” Warren said.

Again on Tuesday, as she had in the past, Warrenpledged that she’ll “be there,” even if proceedings are prolonged.

“All of us in the House and the Senate took the same oath of office,” Warren recently told reporters while stumping in Des Moines, Iowa. “I will follow through on that promise. There are things that are more important than politics. If we have a long trial in Washington, I will be there for that, because that is my responsibility."

Warren now stands among her fellow Democratic contenders as one of the defending front-runners, less than a month’s countdown to go before the Iowa caucuses. Though her recent poll and fundraising numbers have stagnated some, Warren took to The View roundtable Tuesday fueled by a fresh endorsement from one of her erstwhile primary rivals - former Housing and Urban Development Secretary Julián Castro.

Castro - who was the only Latino in the Democratic primary, and one of the first Mexican-American candidates to run for the White House, ended his bid as the books closed on 2019. Monday morning, he announced his support for Warren in a video posted to Twitter, praising her for being “unafraid to fight like hell to make sure America’s promise will be there for everyone.”

As if almost underscoring the point, Warren moved among a studio audience that chanted her name during a commercial break and took selfies with those gathered.

Warren addressed the new endorsement on The View, reiterating how grateful she is for Castro's support. He will also be joining Warren Tuesday evening for a joint rally at Brooklyn’s Kings Theatre in New York City, with more joint and solo events to come, communications director Sawyer Hackett tells ABC News - especially if Warren amongst her fellow sitting senators are pulled off the campaign trail for impeachment.

Warren also lamented the dwindling diversity in the 2020 presidential campaign field saying that the outsized influence of billionaire candidates who have been able to leverage their money to secure critical time in the national spotlight has especially hurt candidates of color. Former presidential candidate California Sen. Kamala Harris suspended her bid last month citing, in part, troubles raising funds to mount a sustained bid.

Hawaii Rep. Tulsi Gabbard, who is of Southeast Asian, Polynesian, and Caucasian descent; entrepreneur Andrew Yang, who is Taiwanese American; and New Jersey Cory Booker and former Massachusetts Gov. Deval Patrick-- who are both African American, would have to net large polling surges before the Friday deadline to qualify for the debate stage.

"I think this is a real problem, and I want to underline in particular the influence of money in this whole process," she told The View co-host Sunny Hostin. The very day that Kamala said, I have to get out of this race because of money is the same day a billionaire bought his way onto the debate stage. We cannot be a party, we cannot be a democracy, in which the only way you get to be president of the United States is you either are a billionaire."