Washington • Sen. Mike Lee of Utah objected Wednesday to passing legislation to protect special counsel Robert Mueller’s investigation, scuttling a bipartisan attempt to ensure President Donald Trump can’t end the probe into whether he or his team colluded with Russia to sway the 2016 election.

Democratic Sens. Chris Coons of Delaware and Cory Booker of New Jersey and Republican Sen. Jeff Flake of Arizona had attempted to pass the bill by unanimous consent, a maneuver that can be blocked by a single senator.

Lee cited a 30-year-old dissent by Supreme Court Associate Justice Antonin Scalia arguing that protecting an independent counsel from presidential power creates a “fourth branch of government.”

Lee warned that the bill to protect Mueller would “fundamentally [undermine] the principle of separation of powers.”

“Prosecutorial authority in the United States belongs in the Department of Justice.” Lee said.

In response to The Salt Lake Tribune’s request for comment, Lee spokesman Conn Carroll said: “What the senator said on the Senate floor is perfect.”

Attempts to pass legislation to protect Mueller's investigation have stalled in Congress, though the Senate Judiciary Committee voted to support such a bill.

Lee and fellow Republicans, including longtime Sen. Orrin Hatch of Utah, have said there’s no need for legislation because Trump wouldn’t fire Mueller or end his probe. Sen.-elect Mitt Romney, who will succeed Hatch, says the investigation must continue unimpeded, though he isn’t sure if legislation is necessary.

Senate Majority Leader Mitch McConnell, R-Ky., said he wouldn’t bring up the Mueller-protection legislation because it was superfluous.

"The president is not going to fire Bob Mueller, nor do I think he should, nor do I think he should not be allowed to finish," McConnell said Tuesday night. "We have a lot of things to do to finish up this year without taking votes on things that are completely irrelevant to outcomes."

Flake, who is leaving office, said Wednesday that his colleagues are blind if they can’t see Trump is already angling to halt Mueller’s investigation.

“With the president tweeting on a regular basis, a daily basis, that the special counsel is conflicted, that he is leading the so-called 12 angry Democrats and demeaning and ridiculing him in every way, to be so sanguine about the chances of him getting fired is folly for us,” Flake said on the Senate floor.

Coons pointed out that the Scalia opinion Lee cited was a dissent on a 7-1 decision by the high court and that the justices ruled the law creating an independent counsel was constitutional. (The law has since expired and the special counsel now is supervised by the attorney general.)

“At the end of the day, leader McConnell has gotten reassurances from the president that he won’t act against Mueller, but those assurances are undermined every single day when President Trump both tweets untrue criticisms of Robert Mueller and his investigation and does other things that are unexpected or unconventional or unjustified,” Coons told MSNBC.

White House press secretary Sarah Huckabee Sanders said Trump has no current plans to fire Mueller but wants the 18-month-old probe to end.