Legislation protecting special counsel Robert MuellerRobert (Bob) Swan MuellerThis week: Mueller dominates chaotic week on Capitol Hill Top Republican considered Mueller subpoena to box in Democrats Kamala Harris says her Justice Dept would have 'no choice' but to prosecute Trump for obstruction MORE was blocked on Wednesday for a second time in the past month.

Sen. Jeff FlakeJeffrey (Jeff) Lane FlakeFlake urges Republicans to condemn 'vile and offensive' Trump tweets Flake responds to Trump, Jimmy Carter barbs: 'We need to stop trying to disqualify each other' Jeff Flake responds to Trump's 'greener pastures' dig on former GOP lawmakers MORE (R-Ariz.), joined by Sens. Christopher CoonsChristopher (Chris) Andrew CoonsDemocrats pledge to fight Trump detention policy during trip to border Trump nominees meet fiercest opposition from Warren, Sanders, Gillibrand Senate Democrats skipping Pence's border trip MORE (D-Del.) and Cory BookerCory Anthony BookerTrump tweets, rally chant dominate Sunday shows as president continues attacks Sunday shows - Fallout over Trump tweets Booker: Trump is 'worse than a racist' MORE (D-N.J.), tried to get consent to schedule the long-stalled legislation for a vote. 

Flake questioned why his colleagues weren't "up in arms" after a string of tweets from President TrumpDonald John TrumpChelsea Clinton announces birth of third child Ukrainian officials and Giuliani are sharing back-channel campaign information: report Trump attacks 'the Squad' as 'racist group of troublemakers' MORE bashing Mueller's investigation into Russian interference in the 2016 presidential election.

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

Trump in a tweet hours before Flake's request blasted Mueller's probe into Russian election interference and possible collusion between the president's campaign and Moscow as the "angry Mueller gang of Dems" and exclaimed that it is "our Joseph McCarthy era."

But GOP Sen. Mike LeeMichael (Mike) Shumway LeeThe Hill's Morning Report — Mueller Time: Dems, GOP ready questions for high-stakes testimony This week: Mueller dominates chaotic week on Capitol Hill Overnight Health Care — Presented by PCMA — Health care moves to center stage of Democratic primary fight | Sanders, Biden trade sharps jabs on Medicare for All | Senate to vote on 9/11 bill next week | Buttigieg pushes for cheaper insulin MORE (Utah) objected to voting on the legislation, arguing the bill had constitutional issues.

"As Justice Scalia explains, we cannot convert an office like this one ... without creating a de facto fourth branch of government fundamentally undermining the principles of the separation of powers that is so core to our liberty," Lee said.

Flake pledged that they would come back to the Senate floor to try to set up the bill for a vote again.

Under the upper chamber's rules, senators can go to the floor to request a vote or passage of any bill or nomination. But any one senator can block their requests. 

The floor drama comes after Senate Majority Whip John CornynJohn CornynGOP wants commitment that Trump will sign budget deal Hillicon Valley: Trump seeks review of Pentagon cloud-computing contract | FTC weighs updating kids' internet privacy rules | Schumer calls for FaceApp probe | Report says states need more money to secure elections Senators introduce legislation to boost cyber defense training in high school MORE (R-Texas) said Republican leadership was measuring support for the bill to try resolve a standoff with Flake, who is voting against judicial nominees until the Mueller protection bill gets a vote. 

"We're whipping that to see where people are. I think the leader needs that information to decide how to manage all the competing demands on our time," Cornyn said when asked about discussions within the Republican caucus about the legislation.

But there is still fierce opposition to the bill within the GOP caucus, and Senate Majority Leader Mitch McConnellAddison (Mitch) Mitchell McConnellThe Hill's Morning Report — Mueller Time: Dems, GOP ready questions for high-stakes testimony Election security to take back seat at Mueller hearing McConnell challenger faces tougher path after rocky launch MORE (R-Ky.) called it a “solution in search of a problem” on Tuesday. 

The president has stepped up his Twitter attacks on Mueller's probe in recent days amid several new revelations, including the special counsel's charge that former Trump campaign chairman Paul ManafortPaul John ManafortUkrainian officials and Giuliani are sharing back-channel campaign information: report Key numbers to know for Mueller's testimony Webb: Questions for Robert Mueller MORE had violated his plea agreement. 

New reports emerged on Tuesday that Manafort's attorney had been sharing information with attorneys for Trump on his former campaign aide's cooperation with the Mueller probe. 

Trump after the midterm elections forced Attorney General Jeff SessionsJefferson (Jeff) Beauregard SessionsThe Hill's 12:30 Report: Trump hits media over 'send her back' coverage House gears up for Mueller testimony Trump's no racist — he's an equal opportunity offender MORE to resign and named Matthew Whitaker, Sessions's chief of staff, as acting attorney general. Whitaker, who has criticized the Mueller probe, is now overseeing it in place of Deputy Attorney General Rod RosensteinRod RosensteinKey numbers to know for Mueller's testimony 10 questions for Robert Mueller What to expect when Mueller testifies: Not much MORE

The Senate Judiciary Committee passed legislation that would protect Mueller, or any other special counsel, in the event he is fired, but the bill has stalled amid opposition from GOP leadership.

The bill would codify Justice Department regulations that say only a senior department official could fire Mueller or another special counsel.

It would give a special counsel an "expedited review" of their firing. If a court determines that it wasn't for "good cause," the special counsel would be reinstated.

Updated at 12:59 p.m.