Several Democrat presidential candidates on Wednesday took to social media to call on Congress to begin impeachment proceeding against President Donald Trump following special counsel Robert Mueller’s press conference about his investigation into Russian interference in the 2016 election.

Sen. Elizabeth Warren (D-MA) declared Mueller’s statement “makes clear” that his report is an “impeachment referral” for Congress to act upon. “They should,” she declared.

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. — Elizabeth Warren (@ewarren) May 29, 2019

The Massachusetts Democrat then listed three areas in which she believes the special counsel left “no doubt” regarding his findings. “1) He didn’t exonerate the president because there is evidence he committed crimes. 2) Justice Department policy prevented him from charging the president with any crimes. 3) The Constitution leaves it up to Congress to act—and that’s impeachment,” she tweeted.

Mueller leaves no doubt:

1) He didn't exonerate the president because there is evidence he committed crimes.

2) Justice Department policy prevented him from charging the president with any crimes.

3) The Constitution leaves it up to Congress to act—and that's impeachment. — Elizabeth Warren (@ewarren) May 29, 2019

Sen. Cory Booker (D-NJ) contended Mueller’s statement makes “clear” that Congress has a “legal and moral” duty to launch impeachment proceedings “immediately. In a follow-up tweet, Booker wrote “Beginning impeachment proceedings is the only path forward,” the White House’s vow to fight subpoenas from House Democrats investigating President Trump and his associates for possible public corruption.

Robert Mueller’s statement makes it clear: Congress has a legal and moral obligation to begin impeachment proceedings immediately. — Cory Booker (@CoryBooker) May 29, 2019

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

Another White House hopeful, former Housing and Developing Sec. Julian Castro (D-TX) also argued Mueller’s remarks make “clear” it is up to lawmakers on Capitol Hill to act on impeachment, tweeting: “No one is above the law—Congress should begin an impeachment inquiry.”

Mueller made clear this morning that his investigation now lays at the feet of Congress. No one is above the law—Congress should begin an impeachment inquiry. — Julián Castro (@JulianCastro) May 29, 2019

Rep. Seth Moulton (D-MA), who launched a longshot bid for the presidency last month, said impeachment hearings should start tomorrow.

Mueller did his job. Now it’s time to do ours. Impeachment hearings should begin tomorrow. https://t.co/9za3s0pqOA — Seth Moulton (@sethmoulton) May 29, 2019

Appearing on MSNBC, South Bend Mayor Pete Buttigieg said of Mueller’s statements: “The message really is over to you Congress. This is as close to an impeachment referral as you could get under the circumstances.”

Former Rep. Robert Francis “Beto” O’Rourke (D-TX) said the special counsel’s findings must yield “consequences, accountability, and justice.”

“The only way to ensure that is to begin impeachment proceedings,” O’Rourke tweeted. “As Mueller reiterates there were “multiple, systemic efforts to interfere in our election,” Trump calls it 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.”

As Mueller reiterates there were "multiple, systemic efforts to interfere in our election," Trump calls it 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. — Beto O'Rourke (@BetoORourke) May 29, 2019

“I think what is clear is that I think it’s a fair inference from what we heard in that press conference that Bob Mueller was essentially referring impeachment to the United States Congress,” said Sen. Kamala Harris (D-CA).

Sen. Bernie Sanders (I-VT) said: “Given the reality that we have a president who believes he is above the law, Congress must continue its investigations. If the House Judiciary Committee deems it necessary, I will support their decision to open an impeachment inquiry.”

While Rep. Eric Swalwell (D-CA), one of Washington’s most vocal proponents of thee Trump-Russia collusion hoax, did not explicitly call for President Trump’s ouster, he did accuse the president of obstructing justice and noted that Congress has the power to act. “We’re not powerless. Our founders gave us a checks & balances system,” he said.

#Mueller has spoken & here’s what we know: ✅ Every American should be concerned about what Russia did (that’s includes you, too, @realDonaldTrump) ✅ Trump is an obstructor who commited crimes ✅ We’re not powerless. Our founders gave us a checks & balances system. #Congress — Eric Swalwell (@ericswalwell) May 29, 2019

Notably, former Vice President Joe Biden’s campaign said he concurs with House Speaker Nancy Pelosi’s (D-CA) position on impeachment, but conceded that it may be “unavoidable” for Congress to oust the president.

.@JoeBiden for President statement on Bob Mueller's comments earlier today: pic.twitter.com/dxiNl2ZmH0 — TJ Ducklo (@TDucklo) May 29, 2019

In his first public remarks about his two-year Russia investigation, Mueller said the inquiry has been closed and he is leaving his role and returning to civilian life.

Speaking at the Justice Department, Mueller reiterated his report’s findings — that there was no evidence to indicate collusion between Moscow and the Trump campaign before the 2016 election, and there were several “episodes” in which President Trump may have obstructed justice with attempts to disrupt the investigation. The report did not clear him on that issue, though Attorney General William Barr and Deputy Attorney General Rod Rosenstein did.

“If we’d had confidence the president didn’t commit a crime, we would have said so,” Mueller said.

The special counsel emphasized that his team could not charge Trump due to longstanding Justice Department policy.

“A president cannot be charged with a federal crime while he is in office,” he said. “That is unconstitutional. Even if the charge is kept under seal and hidden from public view — that too is prohibited.

“The special counsel’s office is part of the Department of Justice and, by regulation, it was bound by that department policy. Charging the president with a crime was therefore not an option we could consider.”

Muller appeared to defer to Congress for possible action based on the law. He said the investigation was necessary, regardless, to preserve evidence and bring charges against co-conspirators who can now be charged.

“The opinion says that the Constitution requires a process other than the criminal justice system for formally accusing a sitting president of wrongdoing,” he said.

Mueller said he does not plan on speaking further about the investigation, precluding any testimony in Congress. House Democrats have been hoping for weeks Mueller would testify to expand on his report’s findings. Other officials, including Barr and former White House counsel Don McGahn, received subpoenas to testify. Both Barr and McGahn defied the subpoena to testify before the House judiciary committee.

“The matters we investigated were of paramount importance,” Mueller added. “When the subject of an investigation obstructs that investigation or lies to investigators it strikes at the government’s effort to find the truth and hold wrongdoers accountable.”

“The report is my testimony,” he said.

The UPI contributed to this report.