Several 2020 Democratic presidential candidates said Wednesday that special counsel Robert Mueller's comments on his Russia investigation should be read by Congress as a call to begin impeachment proceedings against President Donald Trump.

Democratic presidential candidate Cory Booker said Mueller’s statement “makes it clear” that “Congress has a legal and moral obligation" to move forward with impeachment proceedings.

Booker, a senator from New Jersey, was among the first 2020 candidates to weigh in on Mueller’s comments, the first on his two-year-long investigation, in which he declined to clear Trump.

“I’ve been asking for Mueller’s testimony – today he made his views clear,” Booker said on Twitter. "Robert Mueller’s statement makes it clear: Congress has a legal and moral obligation to begin impeachment proceedings immediately.”

Perhaps the most important voice on whether Democrats will attempt to impeach Trump belongs to House Speaker Nancy Pelosi's. She has cautioned Democrats that taking the impeachment path could prove to be helpful to Trump's political fortunes.

On Wednesday, she said "Congress will continue to investigate and legislate to protect our elections and secure our democracy."

Former Vice President Joe Biden, the 2020 Democratic frontrunner, stopped short of calling for impeachment but said that the possibility that House Democrats may have to move might become unavoidable.

"Vice President Biden agrees with Speaker Pelosi that no one would relish what would certainly be a divisive impeachment process, but that it may be unavoidable if this administration continues on its path," the Biden campaign said in a statement. "For all these reasons and many more, Vice President Biden will continue to make the case as to why President Trump should not be re-elected. That is the surefire way to get him out of office."

WASHINGTON, DC - MAY 29: Special Counsel Robert Mueller walks away from the podium after making a statement about the Russia investigation on May 29, 2019 at the Justice Department in Washington, DC. Mueller said that he is stepping down as special counsel and that the report he gave to the attorney general is his last words on the subject.

Mueller in a news conference Wednesday said if his office "had confidence that the president clearly did not commit a crime, we would have said so.”

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"We did not, however, make a determination as to whether the president did commit a crime," Mueller added.

More: Robert Mueller: Charging Trump was 'not an option we could consider'

More: Read the full text of Robert Mueller's comments on the Russia investigation, Trump

Mueller also noted that while Justice Department policy prohibits charging a sitting president with a crime, the Constitution “requires a process other than the criminal justice system to formally accuse a sitting president of wrongdoing”—a reference to Congress’s ability to begin impeachment proceedings.

Mueller suggested in his comments to reporters that he is reluctant to testify publicly saying that his office’s voluminous report was “my testimony.”

This Administration has continued to stonewall Congress’s oversight. Beginning impeachment proceedings is the only path forward. — Cory Booker (@CoryBooker) May 29, 2019

Sen. Elizabeth Warren, another Democrat vying for the 2020 presidential nomination, said Mueller’s statement left it to Congress to act. She was the first major Democratic presidential candidate to call for the House to impeach Trump last month.

“Mueller’s statement makes clear what those who have read his report know: It is an impeachment referral, and it’s up to Congress to act. They should,” Warren said.

Kamala Harris said lawmakers "need to start impeachment proceedings."

It was a rhetorical sharpening from her stance last month following the release of the Mueller report when she said “Congress should take the steps towards impeachment,” while also expressing pessimism that Senate Republicans would act if the Democrat-controlled House impeached the president.

Harris said Mueller's comment that it was "not an option" to indict Trump because of a DOJ's Office of Legal Counsel finding that prohibits the prosecution of a sitting president should be eye-opening to lawmakers.

"We learned a few things today," Harris said. "Most importantly, we learned that the special counsel did not return an indictment because of that memo. But for that memo, it's a fair inference from what we heard from Bob Mueller, is that there would have been indictments returned against this president."

There must be consequences, accountability, and justice. The only way to ensure that is to begin impeachment proceedings. — Beto O'Rourke (@BetoORourke) May 29, 2019

South Bend Mayor Pete Buttigieg told NBC News that Mueller's remarks were "as close to an impeachment referral as you could get under the circumstances."

"The message really is, 'Over to you, Congress,'"

Former Rep. Beto O’Rourke noted Mueller concluded there were “multiple, systemic efforts to interfere in our election," yet Trump repeatedly called the investigation a hoax.

“He invited these attacks, obstructed the investigation into them & told Putin there will be no consequences for launching a concerted attack on our political system,” O’Rourke tweeted. “There must be consequences, accountability, and justice. The only way to ensure that is to begin impeachment proceedings.”

Sen. Kirsten Gillibrand earlier this month told Politico she thought that impeachment "should be left on the table" while also endorsing Pelosi's approach as "smart." After Mueller's press briefing Wednesday, the New York senator said it was time for Congress to act.

"Combined with the fact that Robert Mueller clearly expects Congress to exercise its constitutional authority and take steps that he could not, it's time for Republicans and Democrats to begin impeachment hearings and follow the facts wherever they may lead," she said. "We cannot let this president defy basic accountability measures built into our Constitution."

Washington Gov. Jay Inslee, another Democratic presidential candidate, also took to social media to declare “Robert Mueller made it clear: No exoneration.”

“Donald Trump and William Barr lied about the Mueller report.” Inslee added.

Former HUD Secretary Julian Castro said that Mueller left his investigation "at the feet of Congress."

"No one is above the law – Congress should begin an impeachment inquiry," Castro said.

Montana Gov. Steve Bullock called on Congress to oversight of Trump and his administration, but like Biden, stopped short of endorsing impeachment.

"As a former attorney general, I know that no individual is above the law," Bullock said. "While Congress exercises its oversight authority, it is important to remember what Americans are focused on."

Robert Mueller made it clear: No exoneration. — Jay Inslee (@JayInslee) May 29, 2019

Trump offered a different reading on Mueller’s comments.

“Nothing changes from the Mueller Report,” Trump tweeted. “There was insufficient evidence and therefore, in our Country, a person is innocent. The case is closed! Thank you.”

Nothing changes from the Mueller Report. There was insufficient evidence and therefore, in our Country, a person is innocent. The case is closed! Thank you. — Donald J. Trump (@realDonaldTrump) May 29, 2019

This article originally appeared on USA TODAY: 'Begin impeachment proceedings immediately': 2020 Dems call for Congress to act after Mueller speech