As former special counsel Robert Mueller testified in the House about his report on Russian interference in the 2016 presidential campaign, Democratic presidential candidates used his report Wednesday to call for impeachment proceedings against President Donald Trump.

Speaking at the NAACP convention in Detroit, senators and 2020 candidates Elizabeth Warren and Cory Booker said Mueller had already laid out a persuasive case that the president had broken the law by trying to obstruct Mueller's probe.

While some House Democrats said they were hoping to use Mueller's testimony to build a stronger public case for impeachment, Warren said that time is already here.

"I understand that there are people who for political reasons say it's not where we want to be. But my view is some things are above politics," Warren told the crowd. "This is a moment in history, and every single person in Congress should be called on to vote and then to live with that vote for the rest of their lives."

The Massachusetts senator told reporters afterward that "the Constitution is clear. No one is above the law, and that means the president of the United States. I believe it’s time for Congress to bring articles of impeachment against this man.”

Booker, D-N.J., said he believed the Mueller report spelled out behaviors of “deceit” and “instructing people to lie” and indicated that the House should begin impeachment proceedings.

Sen. Bernie Sanders of Vermont said he hadn’t seen any of Mueller’s appearance but wasn’t surprised to hear the former special counsel had testified that Trump wasn’t exonerated by his report. “We know for a fact that the president did everything he could to obstruct the Mueller investigation so I’m not quite shocked at what he said,” Sanders said.

Sen. Kamala Harris, D-Calif., repeated her assertion that there were very clear instances of obstruction of justice outlined in the Mueller report, and that regardless of the position of the president and Attorney General William Barr, “the American people are smart enough to know what is and what is not truth.”

Mayor Pete Buttigieg of South Bend, Indiana, told reporters at the event he was in favor of beginning impeachment proceedings, but cautioned they'd likely hit a roadblock in the Republican Senate.

"Well, we'll see what the testimony reveals but there is more than enough in that report to interpret it as an impeachment referral," Buttigieg said. "I believe that an impeachment inquiry would bring more facts to light. I also believe that the Republican Senate will not act. And so I'm focusing on the best thing I can do about the Trump presidency, which is to defeat it in November of 2020."

New York Senator Kirsten Gillibrand addressed Mueller's appearance during a foreign policy speech in Chicago Wednesday afternoon.

"Today we heard directly from the special counsel that Trump’s claims of 'total exoneration' are wrong, and not what his report said," Gillibrand said. "I believe that Congress should begin impeachment proceedings to continue to get to the truth."

Was there anything new any new information that you learn from the special counsel?

After the speech, Gillibrand was asked if she thought new information emerged from Mueller's testimony.

"I think, for someone who's read the Mueller report? No. But I think from a lot of people who have not read the report, yes. And I think for him to so clearly state that President Trump was not exonerated in his report on obstruction of justice is a fact that a lot of Americans do not realize is true, because President Trump keeps saying he's been exonerated," Gillibrand told NBC News. "He's been lying to the American public."