Washington • Sen. Orrin Hatch says he would vote against legislation that would thwart the firing of special counsel Robert Mueller but adds that President Donald Trump wouldn’t take that action because it could lead to possible impeachment.

I believe it is in President Trump’s best interest to allow the investigation to run its course, because I believe it will vindicate him,” Hatch said in an op-ed published in Wednesday’s Wall Street Journal.

“It is in the country’s best interest, because it will provide definitive answers to questions that have embroiled our politics now for over a year. Firing Mr. Mueller would be a grave error. It would trigger a crisis, possibly even impeachment. It would threaten many of the administration’s accomplishments and make continued progress virtually impossible.”

While Hatch's position is hardly unusual among U.S. lawmakers, even Republicans, it isn't often that GOP senators use the word "impeachment."

The Senate Judiciary Committee is expected to vote this week on legislation that would prohibit any president from firing a special counsel, allowing the counsel to seek a judicial review by three judges if such action is taken. While the White House has said Trump has no intention to fire Mueller, Trump has reportedly considered doing so as the investigation continues into Russia’s meddling into the 2016 election and whether Trump’s team had any hand in the effort.

Senate Judiciary Committee Chairman Chuck Grassley, R-Iowa, plans to take a vote on the legislation Thursday even as Senate Majority Leader Mitch McConnell, R-Ky., vows that he won’t take up the bill on the Senate floor.

Hatch says the legislation is unconstitutional because it allows a special counsel to be above the government’s three branches and gives the counsel unilateral power.

Many, myself included, have supported independent prosecutors in the past,” Hatch wrote in The Journal. “Experience has shown that was a mistake. Freed from political accountability and meaningful oversight, independent prosecutors become a law unto themselves.”

Hatch’s Senate colleague Mike Lee, R-Utah, also says he opposes the legislation because it’s unconstitutional and “political expedience can never trump the Constitution.”

Supporters of the legislation argue it is necessary to ensure no one is above the law,” Lee said in an op-ed this week in USA Today, “but the Constitution is the highest law of the land, and the Constitution provides that only the president can exercise executive power.”

Lee also said Mueller’s investigation should run its course in a “timely fashion.”