Nearly every senator returned to Washington Monday evening in time to attend a closed-door joint caucus to discuss filibuster rules.

Ninety-seven senators participated in the mandatory quorum call Senate Majority Leader Harry Reid Harry Mason ReidSenate Republicans signal openness to working with Biden Mellman: The likely voter sham Bottom line MORE (D-Nev.) requested ahead of the 6 p.m. caucus in the Old Senate Chamber.

The GOP cloak room said Sen. Marco Rubio Marco Antonio RubioHillicon Valley: DOJ indicts Chinese, Malaysian hackers accused of targeting over 100 organizations | GOP senators raise concerns over Oracle-TikTok deal | QAnon awareness jumps in new poll Intelligence chief says Congress will get some in-person election security briefings Republican Senators raise concerns over Oracle-TikTok deal MORE (Fla.) was the only missing Republican, while Sens. Jeanne Shaheen Cynthia (Jeanne) Jeanne ShaheenSenate Democrats introduce bill to sanction Russians over Taliban bounties Trump-backed candidate wins NH GOP Senate primary to take on Shaheen Democratic senator urges Trump to respond to Russian aggression MORE (N.H.) and Bob Menendez Robert (Bob) MenendezKasie Hunt to host lead-in show for MSNBC's 'Morning Joe' Senators ask for removal of tariffs on EU food, wine, spirits: report VOA visa decision could hobble Venezuela coverage MORE (N.J.) were the absent Democrats.

ADVERTISEMENT

Reid has threatened to use the “nuclear option” — changing the Senate rules to allow presidential nominations to proceed with a simple-majority vote instead of a 60-vote super-majority — in order to thwart Republican obstruction on seven of President Obama’s cabinet nominees.

Sen. John McCain John Sidney McCainKelly's lead widens to 10 points in Arizona Senate race: poll COVID response shows a way forward on private gun sale checks Trump pulls into must-win Arizona trailing in polls MORE (R-Ariz.) told reporters heading into the joint caucus that lawmakers had agreed to the outlines of a compromise on nominees although a senior Democratic aide disputed the claim.

“We’ll go over those outlines,” said McCain. “I think it’s very important that we give those proposals that our supported by a number of Republicans at least the consideration of our colleagues on both sides of the aisle.

McCain said some Democrats are familiar with the details of the proposed compromise.

“They know it and many of them are supportive of it but we’ll see,” he said.

ADVERTISEMENT

A senior Democratic aide disagreed strongly.

“There’s no deal,” said the aide, who explained that McCain proposed swapping in two nominees to the National Labor Relations Board to replace Sharon Block and Richard Griffin, Jr., whom President Obama put on the board with recess-appointments. The D.C. Circuit Court later ruled the move unconstitutional.

McCain has shared the plan with senior White House officials.

“They’d like to see it resolved as well but they know it’s largely a Senate issue,” he said.

In the fight over Obama's nominees, Democrats have argued that the president should be able to select his own team and that executive branch nominees shouldn’t be held to a 60-vote threshold. Reid has emphasized that the rules change would not cover judicial nominees.

Republicans have argued that they are simply exercising the rights in the Constitution for the Senate to “advise and consent” on executive nominees and that changing the rules would harm minority rights in the Senate.

They've also threatened to retaliate if they regain the Senate majority.

Senate Minority Leader Mitch McConnell Addison (Mitch) Mitchell McConnellSenate Republicans signal openness to working with Biden Hillicon Valley: DOJ indicts Chinese, Malaysian hackers accused of targeting over 100 organizations | GOP senators raise concerns over Oracle-TikTok deal | QAnon awareness jumps in new poll The Hill's Campaign Report: Biden asks if public can trust vaccine from Trump ahead of Election Day | Oklahoma health officials raised red flags before Trump rally MORE (R-Ky.) said last week that he was disappointed the joint caucus was scheduled for Monday instead of Tuesday because not all lawmakers return from spending the weekends in their homes states by Monday evening.

Seven nominees are at issue: Richard Cordray as director of the Bureau of Consumer Financial Protection; Griffin, Block and Mark Pearce to the National Labor Relations Board; Fred Hochberg to be president of the Export-Import Bank; Thomas Perez Thomas Edward PerezClinton’s top five vice presidential picks Government social programs: Triumph of hope over evidence Labor’s 'wasteful spending and mismanagement” at Workers’ Comp MORE to be secretary of Labor; and Gina McCarthy Regina (Gina) McCarthyOVERNIGHT ENERGY: Energy Department proposes showerhead standards rollback after Trump complaints | Interior memo scaling back bird protections is 'contrary to law,' court rules | Former EPA chiefs call for agency 'reset' Former EPA chiefs call for agency 'reset' Azar arrives in Taiwan amid tensions with China MORE to be administrator of the Environmental Protection Agency.

Cordray and the NLRB nominees are the most controversial.

Procedural votes on those nominations are expected to start Tuesday, but senators are hoping to reach a deal to allow up-or-down votes to avoid the “nuclear option.”

This story was updated at 6:39 p.m.