Legislation protecting special counsel Robert MuellerRobert Swan MuellerSasse: US should applaud choice of Mueller to lead Russia probe MORE was blocked on Wednesday for a second time in the past month.

Sen. Jeff FlakeJeffrey (Jeff) Lane FlakeTrump suggests Heller lost reelection bid because he was 'hostile' during 2016 presidential campaign Live coverage: Trump delivers State of the Union Sasse’s jabs at Trump spark talk of primary challenger MORE (R-Ariz.), joined by Sens. Christopher CoonsChristopher (Chris) Andrew CoonsTrump got in Dem’s face over abortion at private meeting: report Live coverage: Trump delivers State of the Union Actor Chris Evans meets with Democratic senators before State of the Union MORE (D-Del.) and Cory BookerCory Anthony BookerSanders expected to announce exploratory committee next week Bill Maher to Dems: ‘Let’s not eat our own’ in 2020 Dems ready aggressive response to Trump emergency order, as GOP splinters 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 TrumpGillibrand backs federal classification of third gender: report Former Carter pollster, Bannon ally Patrick Caddell dies at 68 Heather Nauert withdraws her name from consideration for UN Ambassador job 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 LeeSenate approves border bill that prevents shutdown Push for paid family leave heats up ahead of 2020 New act can help us grapple with portion of exploding national debt 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 CornynPoll shows competitive matchup if O’Rourke ran for Senate again On The Money: Trump declares emergency at border | Braces for legal fight | Move divides GOP | Trump signs border deal to avoid shutdown | Winners, losers from spending fight | US, China trade talks to resume next week How the border deal came together 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 McConnellDems ready aggressive response to Trump emergency order, as GOP splinters Green New Deal Resolution invites big picture governing ‘Contingency’ spending in 3B budget deal comes under fire 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 ManafortMake the special counsel report public for the sake of Americans Paul Manafort should not be sentenced to 20 years in prison Mueller recommends Manafort serve at least 19 years in prison 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 Morning Report — Presented by the American Academy of HIV Medicine — Trump, Congress prepare for new border wall fight The Memo: Trump and McCabe go to war McCabe book: Sessions once said FBI was better off when it 'only hired Irishmen' 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 Jay RosensteinEx-federal prosecutor: I would have 'owned' wearing a wire to record Trump The embarrassing return of Andrew McCabe The Hill's Morning Report — Presented by the American Academy of HIV Medicine — Trump, Congress prepare for new border wall fight 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.