WASHINGTON (CBS) — Sen. Ed Markey is the latest Massachusetts Democrat to call for Congress to start the impeachment process against President Donald Trump, one day after Special Counsel Robert Mueller testified in the House of Representatives about the Russia investigation.

Mueller reiterated that his report did not exonerate Trump on obstruction of justice, despite the president’s claims.

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“The Special Counsel’s testimony and events of the past few weeks have led to the undeniable conclusion that it is time for the House of Representatives to begin a formal impeachment proceeding against President Trump,” Markey said on the Senate floor Thursday. “I stand here today because I believe we have reached the moment where we must stand up for the survival of our democracy.”

Two people have announced primary challenges against Markey, who is up for re-election in 2020.

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It is up to the House to initiate impeachment proceedings, something that House Speaker Nancy Pelosi has so far been unwilling to do despite calls from dozens of Democratic representatives.

“I do not come to this decision lightly. An impeachment proceeding against the President of the United States is a matter of the highest constitutional magnitude,” Markey said. “But when the evidence demonstrates that the President of the United States obstructed the Special Counsel’s investigation, and when the facts and the evidence demonstrate that the President of the United States is continuing to obstruct justice — seeking to derail a legitimate congressional investigation into the lawfulness of his conduct while in office — then the Congress must do its constitutional duty and act.”

Rep. Katherine Clark, of Massachusetts’ fifth district, also on Thursday said it was time for Congress to start impeachment proceedings. She is the vice chair of the House Democratic caucus.

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Congresswoman Lori Trahan, who represents the state’s third district, declared her support for an impeachment inquiry on Wednesday. Sen. Elizabeth Warren and Massachusetts Representatives Ayanna Pressley, Jim McGovern, Seth Moulton and Joe Kennedy have already called for impeachment to begin.