Sen. Elizabeth Warren on Friday became the first Democratic presidential candidate to call on the House to begin impeachment proceedings against President Donald Trump.

Warren, of Massachusetts, said her announcement was based on the findings of special counsel Robert Mueller.

"The severity of this misconduct demands that elected officials in both parties set aside political considerations and do their constitutional duty," she tweeted. "That means the House should initiate impeachment proceedings against the President of the United States."

The severity of this misconduct demands that elected officials in both parties set aside political considerations and do their constitutional duty. That means the House should initiate impeachment proceedings against the President of the United States. — Elizabeth Warren (@ewarren) April 19, 2019

In an interview Friday night on "The Rachel Maddow Show," Warren said starting impeachment proceedings was a point of principle.

"The report is absolutely clear that a foreign government attacked our electoral system to help Donald Trump," she said. "He welcomed that help, and then when it was investigated by our own federal authorities Donald Trump took multiple steps to try to obstruct justice."

Before Warren's statement, another 2020 candidate, Sen. Amy Klobuchar, D-Minn., a member of the Senate Judiciary Committee, told reporters at a campaign stop in New Hampshire that the senators in the race seemed to be choosing their words carefully on the issue.

"I think you’ve seen all the senators are very cautious about talking about this because we would be the jury if there was any kind of an action brought over from the House," she said, adding that "the key thing" for her was to have special counsel Robert Mueller testify before the Judiciary Committee.

A spokeswoman for House Speaker Nancy Pelosi, D-Calif, responding to Warren's call, said, “As the speaker has said repeatedly, one step at a time."

"We’re focused on getting the full unredacted version of the report and its underlying documents — as well as hearing from Mueller," the spokeswoman said in a statement. "The report raises more questions and concerns that we believe the American people deserve answers to."

Tom Steyer, a billionaire Democratic donor who has led a crusade to impeach Trump, called Warren "one of the people in Washington who has the moral courage to do what's right."

"Eight million Americans are thanking her for her leadership and for taking a strong stand against this dangerous President," he said in a statement Friday.

Steyer had flirted with a presidential run himself but ruled it out in January, choosing instead to dedicate himself to the impeachment effort through his organization, "Need to Impeach."

Other Democratic presidential candidates said Friday that Trump's conduct as detailed in the redacted version of the report made impeachment worth discussing, although one, Sen. Bernie Sanders, I-Vt., ignored questions from reporters on the subject at a campaign stop in Greenville, South Carolina.

Pete Buttigieg, the mayor of South Bend, Indiana, told NBC News on Friday that while there's “evidence that this president deserves to be impeached,” he is not in Congress so will leave it those who are to decide whether to pursue proceedings.

Rep. Eric Swalwell, D-Calif., who recently announced a White House bid, said on MSNBC Friday that impeachment is "a conversation we have to have as far as holding this president accountable," but when asked to clarify whether that means he supports impeachment, he said, "I'm for bringing Bob Mueller in and see what the evidence is."

Julián Castro, a former Housing and Urban Development secretary under President Barack Obama, tweeted his view that it "would be perfectly reasonable for Congress to open up impeachment hearings against President Trump. Robert Mueller clearly left that option in the hands of Congress."

Sen. Kamala Harris, D-Calif., did not rule it out in an interview Thursday on MSNBC's "All in With Chris Hayes."

"I think that there is definitely a conversation to be had on that subject, but first I want to hear from Bob Mueller," Harris said, "and really understand what exactly is the evidence that supports the summary that we have been given today."

As Democrats continue to sift through the redacted Mueller report, some lawmakers who previously downplayed the idea of impeaching Trump said the investigation’s findings may require them to initiate such proceedings in the House.

House Oversight Committee Chairman Elijah Cummings, D-Md., said in an interview on MSNBC's "Morning Joe" on Friday that the Mueller report shows that what Trump has done is "at least 100 times worse" than the actions that led to the impeachment of President Bill Clinton in 1998. Cummings previously had called talk of impeachment premature, but said Friday, "We may very well come to that very soon."

"We’ve got to go against this, we've got to expose it. A lot of people keep asking about the question of impeachment," Cummings said.

"But right now, let's make sure we understand what Mueller was doing, understand what Barr was doing, and see the report in an unredacted form, and all of the underlying documents," he said, referring to Attorney General William Barr.

House Intelligence Committee Chairman Adam Schiff, D-Calif., in an interview on MSNBC's "Andrea Mitchell Reports" Friday, said that the obstruction material laid out by the special counsel is "damning enough," but that Congress needs to take some time to digest the seriousness of the report to determine the right course of action.

Schiff added that "here we are less than 24 hours after the report, and I think we need as a caucus to have a discussion about what's the import of this and what’s the way forward."

Rep. Ro Khanna, D-Calif, said Friday on Fox News that the decision on whether to pursue impeachment rests with Pelosi.

"There is only one person who matters — Nancy Pelosi," he said. "She sets the agenda for House Democrats. Every member of Congress has an opinion, but Nancy Pelosi is going to set the agenda. And she has said, let's have Mueller testify, let's have the committees do their work and gather evidence. But it is premature to be making any other judgments."

Several hours after the 448-page redacted report was released to Congress and the public on Thursday, talk of impeachment gathered steam among some rank-and-file Democrats, including freshman Rep. Alexandria Ocasio-Cortez, D-N.Y., who announced on Twitter that she will sign on to an impeachment resolution introduced by Rep. Rashida Tlaib, D-Mich., in March.

House Judiciary Committee Chairman Jerrold Nadler, D-N.Y., who in March said he had a “high bar” for impeachment, also did not rule out such a scenario Thursday. His committee has the power to initiate an impeachment inquiry and proceedings.

Asked if holding Trump accountable means impeachment, Nadler said, "That's one possibility — there are others."

Some Democrats said that impeachment would be too divisive, and that the issue of whether to keep Trump as president should be left up to voters in the 2020 election.

"In my view, there's an even better political process coming right down the road on almost the same time frame and that's the elections of 2020,” Sen. Angus King, an Independent from Maine who caucuses with the Democrats, told CNN Friday. "For Congress to go through an impeachment process would be, it would take probably 18 months, which would lead right up to the election. And it would be divisive.”

On Thursday, House Majority Leader Steny Hoyer, D-Md., reportedly told CNN that “impeachment is not worthwhile at this point.” Afterward, he appeared to walk that comment back, saying that “all options ought to remain on the table.”

Congress must have the full report & all underlying evidence in order to determine what actions may be necessary to ensure that the Congress & the American people have all the info they need to know the truth & all options ought to remain on the table to achieve that objective. — Steny Hoyer (@LeaderHoyer) April 19, 2019

Articles of impeachment would require a simply majority to pass in the House, which is currently controlled by Democrats. The Senate, on the other hand, which has the power to remove a president through a two-thirds vote, is highly unlikely to convict Trump and remove him from office because the chamber is controlled by Republicans. Only two presidents have been impeached in U.S. history: Clinton in 1998, and President Andrew Johnson in 1868. Neither was convicted in the Senate.