Senator Elizabeth Warren of Massachusetts called for Congress to begin impeachment proceedings against President Trump after the release of the redacted Mueller report last month, arguing that Robert S. Mueller, the special counsel, “put the next step in the hands of Congress.”
But many of her competitors stayed quiet on the issue, amid fear that a failed effort would strengthen Mr. Trump’s re-election chances, and because voters were not clamoring for impeachment on the campaign trail. Many also argue that the Republican majority in the Senate is unlikely to impeach Mr. Trump, making a House effort to do so a moot point.
Beto O’Rourke, former representative of Texas, had been among those who suggested that Mr. Trump’s fate was best left to voters. But now he is calling for Congress to move toward impeachment, arguing that Democrats should not worry that it would antagonize the president’s base.
“If we do nothing because we are afraid of the polls or the politics, or the repercussions in the next election, we will set a precedent that, in fact, some people, because of the position of power and public trust that they hold, are above the law,” he said at a CNN town hall event in Iowa on Tuesday.
Here’s a look at what the other candidates for the Democratic nomination have said about impeachment.
The argument in favor
Senator Kamala Harris of California has said that she thinks Congress “should take the steps toward impeachment,” though she was added that she was realistic about the probable outcome in the Senate.
“I think we have very good reason to believe that there is an investigation that has been conducted, which has produced evidence that tells us that this president and his administration engaged in obstruction of justice,” she said at a CNN event last month.
In the same vein, Ms. Warren has argued that “to ignore a president’s repeated efforts to obstruct an investigation into his own disloyal behavior would inflict great and lasting damage on this country.”
Representative Seth Moulton of Massachusetts called for starting an impeachment inquiry on MSNBC on Tuesday.
“We have a constitutional responsibility to act as a check on the executive,” he said, even if the effort does not succeed because of Republican opposition.
Julián Castro, the former housing secretary and former mayor of San Antonio, said on CNN last month that “it would be perfectly reasonable” for Congress to begin impeachment proceedings.
“It’s clear that Bob Mueller, in his report, left that in the hands of Congress,” he argued.
Representative Eric Swalwell of California, who sits on the Judiciary and Intelligence Committees, said on Twitter on May 6 that “impeachment may be the only road to save our country.”
Wayne Messam, mayor of Miramar, Fla., supports impeachment as well.
Would that play into Trump’s hands?
Senator Bernie Sanders of Vermont has said that if Democrats focus on impeachment and the Mueller report for the duration of the campaign, at the expense of talking about issues like health care and climate change, it could work to Mr. Trump’s advantage.
Representative Tulsi Gabbard of Hawaii has said that she doesn’t think impeachment is the way to defeat Mr. Trump. On Fox News last month, she voiced concerns about the “continued divisiveness and putting partisan political interests ahead of the interest of the people.”
Andrew Yang, a businessman from New York with a sizable online following, said on Twitter last month that his focus is on beating Mr. Trump at the ballot box “and solving the problems that got him elected in the first place.”
Marianne Williamson, a self-help author who is calling for a “moral and spiritual awakening in the country,” has said that Mr. Trump is “goading us to impeach him.”
Most are taking a wait-and-see approach
Senator Cory Booker of New Jersey has said it is premature to discuss impeachment, since lawmakers still do not have an unredacted version of the Mueller report and Mr. Mueller has not testified on Capitol Hill since its release.
“There’s a lot more investigation that should go on before Congress comes to any conclusions like that,” he said during a campaign event in Nevada last month.
John Hickenlooper, the former governor of Colorado, also said last month that the decision to move forward with impeachment proceedings shouldn’t be made until Democrats receive an unredacted version of the report.
Senator Kirsten Gillibrand of New York told Politico this month that impeachment “should be left on the table,” but she also said that Speaker Nancy Pelosi’s efforts to slow the rush to impeach are smart.
Joseph R. Biden Jr., the former vice president, said in an interview with “Good Morning America” on April 30 that for now, Congress should continue its own investigations. But if the administration tries to block those inquiries, Congress would have “no alternative” but to “go to the only other constitutional resort they have, which is impeachment,” Mr. Biden said.
Senator Michael Bennet of Colorado said on “Face the Nation” on May 12 that he was “not ready to say the president should be impeached.”
Gov. Steve Bullock of Montana did not answer directly when asked whether he supports impeachment during his first television interview as a candidate, conducted last week.
“I support Congress doing full investigations as they should. That’s their job,” Bullock said. He added, “People are more worried about, ‘Am I going to be able to afford college? Is my kid going to get sick?’”
John Delaney, a former congressman from Maryland, applauded Representative Justin Amash, a Republican from Michigan, for calling for Mr. Trump’s impeachment this week, without repeating the call himself.
Pete Buttigieg, mayor of South Bend, Ind., said during a CNN town hall event last month that Mr. Trump had “made it pretty clear he deserves impeachment.” But he said he would leave it to lawmakers to “figure out.”
Bill de Blasio, mayor of New York, said on WNYC last month that he was “worried about people putting a lot of energy into … hoping for an impeachment proceeding that is not on the horizon when we should be thinking about the issues facing us right now.”
Most candidates have said they could reassess their views once the open investigations conclude. Representative Tim Ryan of Ohio, Gov. Jay Inslee of Washington and Senator Amy Klobuchar of Minnesota have said they are waiting for the investigations to play out.
“There could come out new facts that would make impeachment a much more realistic and immediate option,” Mr. de Blasio said on WNYC. “But today it does not exist.”