Congressman Peter Welch (D-Vt.) said publicly for the first time Monday that President Donald Trump would be committing an "impeachable" offense if he were to seek the removal of Special Counsel Robert Mueller.

Asked what Congress should do if Trump fired Deputy Attorney General Rod Rosenstein in order to remove Mueller, Welch said, "That would be grounds for Congress taking up the impeachment questions."

In recent weeks, Trump has repeatedly criticized Mueller, whom Rosenstein appointed last May to investigate alleged ties between the president's 2016 campaign and Russia. While Trump cannot directly terminate the special counsel or end his investigation, he could order the acting attorney general — at the moment, Rosenstein — to do so.

But, according to Welch, "That would be obstruction of justice. The president is not above the law. No citizen is above the law."

Asked whether he would personally file articles of impeachment, Welch said, "I think it would be impeachable, and I would very likely support impeachment if he interfered with the investigation by firing [Mueller]."

Until now, Welch and Vermont's other two congressional delegates — Sen. Patrick Leahy (D-Vt.) and Sen. Bernie Sanders (I-Vt.) — have largely avoided weighing in on the impeachment question. Last December, Welch voted against a procedural motion to debate impeachment. At the time, Welch said such a move would "undercut" Mueller's investigation.

Welch said Monday that he still does not know whether Trump has obstructed justice or committed other impeachable offenses to date.

"I mean, I really deplore his behavior because it's crossing lines," he said. "Whether it meets the legal definition or the constitutional definition [of obstruction of justice], let's follow the facts. The best chance for us to get credible facts is to maintain our support for the independent investigation by Mueller."

To that end, Welch and Congressman Charlie Dent (R-Pa.) on Friday introduced the first bipartisan legislation in the House seeking to protect Mueller.

The Special Counsel Independence and Integrity Act would allow removal "only for misconduct, dereliction of duty, incapacity, conflict of interest, or other good cause, including violation of policies of the Department of Justice." The bill would limit authority to remove a special counsel only to the most senior, non-recused, Senate-approved DOJ official. And it would allow a special counsel to contest his or her firing before a three-judge court. It would also preserve any material gathered by a special counsel over the course of an investigation.

Welch said he was inspired to take action by Trump's recent Twitter posts attacking Mueller and Rosenstein.

"Everyone knows there's a potential for the president to fire Mueller," he said. "We'd be deaf, dumb and blind if we didn't have an awareness of that."

Welch's legislation, H.R.5505, is identical to S.2644, a bipartisan measure introduced in the Senate by Sen. Lindsey Graham (R-S.C.), Sen. Christopher Coons (D-Del.), Sen. Thom Tillis (R-N.C.) and Sen. Cory Booker (D-N.J.). Leahy and Sanders both support that bill, according to their respective spokespeople. The Senate Judiciary Committee, on which Leahy serves, could take it up this Thursday.

"Nearly every day the President’s tweets remind us of the urgent need to protect the independence of the Special Counsel," Leahy said in a written statement. "And just last week we learned the President believes he has the authority to fire the Special Counsel, which would violate existing regulations and almost certainly constitute obstruction of justice." Leahy added that he was hopeful the Judiciary Committee would pass the legislation "without adding harmful, partisan amendments, and without delay."

Welch said that, even though it was unlikely that the Republican-dominated House would take up his version of the bill, its introduction — with a Republican cosponsor — sent an important signal to Trump.

"It has immediate practical consequences," Welch maintained. "It's a Republican putting his name on a bipartisan bill to protect the special counsel. And it's an indication that Trump's ability to completely count on blind support from his party is being challenged."

Disclosure: Paul Heintz worked as Peter Welch’s communications director from November 2008 to March 2011.