Outgoing Arizona Senator Jeff Flake said Nov. 14 he would stall the confirmation of federal judges if Senate Leader Mitch McConnell didn’t allow a vote on legislation that would protect Special Counsel Robert Mueller from presidential interference.

Politicians and pundits have raised concerns about the potential that Mueller would be fired since before President Donald Trump demanded Attorney General Jeff Sessions’s resignation last week following midterm elections. Flake told CNN that despite assurances he received that Mueller isn’t in jeopardy, “That may have been an arguable position before last week. But it is not arguable anymore.”

Flake, a member of the Senate Judiciary Committee, said he would not vote to advance President Donald Trump’s judicial nominees from the committee nor would he vote to confirm them on the Senate floor without a vote on the Mueller bill.

The bill would put into law a current policy that only a senior Justice Department official or another special counsel to fire Mueller, and additionally includes an expedited review process that would reinstate Mueller if no “good cause” were found. The law would apply to all future special counsels as well.

Currently, 21 nominees await committee approval and 32 face a Senate confirmation vote, Flake said from the Senate floor. Republicans hold an 11-10 majority on the committee.

It’s not yet clear if a second GOP senator would join Flake in opposing full confirmation votes to get the bill to a vote. Assuming all Democratic senators vote against confirmation, an additional GOP member is required to create a 51-49 majority that would bypass Vice President’s Mike Pence’s tie-breaking vote as president of the Senate. Senator Susan Collins said on Nov. 9 that she felt the legislation was necessary, but hadn’t stated any conditions or ultimatums. However, given her support, it’s likely the legislation would pass if a vote were called.

Session’s interim replacement, Matt Whitaker, asserted in a number of public statements in 2017, before joining the Justice Department, the illegitimacy of the Russian election interference probe led by Mueller, and suggested ways to shut it down without firing the former FBI head.

The threat followed an effort by Flake and Senator Chris Coons, a Democrat with whom Flake often allies across the aisle, to force a Senate vote earlier in the day. The legislation has been pending since April, after Flake, Coons, and two other senators, one from each party, hammered out an agreement in the Judiciary Committee.