A single senator vowed Monday night to delay the Senate from debating a must-pass, $700 billion defense bill until he is promised a vote to force Congress to pass an authorization for use of military force against extremist groups within six months.

A growing number of lawmakers have been calling for Congress to pass a new AUMF as the war in Afghanistan drags close to its 17th year. But Sen. Rand Paul (R-Ky.) has largely been alone in his quest to force a deadline on Congress, as the chief agitators for a new AUMF, Sens. Tim Kaine (D-Va.) and Jeff Flake (R-Ariz.), have expressed a firm preference for crafting such a measure in the Senate Foreign Relations Committee. Paul sits on that panel and its chairman, Bob Corker (R-Tenn.), has promised to schedule an AUMF debate soon.

Paul was also alone on the Senate floor Monday night as he pledged to "sit on the floor, in silent protest . . . for as long as needed to ensure Congress do its duty, and vote on ending these wars." He stressed that he would object to "all procedural moves and amendments" until his AUMF measure was guaranteed a vote.

But less than an hour after issuing his threat, Paul and Senate Majority Leader Mitch McConnell (R-Ky.) appeared to have struck a deal, guaranteeing Paul four hours on Tuesday to state his AUMF case on the Senate floor. In an emailed statement sent shortly after, Paul nonetheless pledged to "continue to fight, and if necessary, object, to continue this debate, secure a vote and force Congress to do its duty."

In practical terms, Paul's protesting power is limited. On Monday evening, the Senate voted 89 to 3 to advance the defense bill to the next stage of debate. The next procedural vote can take place early Wednesday morning, and if a quorum of senators are present, Paul will be hard-pressed to stop progress on the bill. Paul could resume his protest at later stages of the debate — but again, procedural time constraints will ultimately frustrate his efforts.

In the process though, his threats could complicate matters for lawmakers who were hoping to secure votes on high-profile amendments they want to attach to the defense bill.

On Monday, bipartisan teams of senators introduced measures to push back on President Trump's order to ban transgender troops from serving openly in the military, and to increase sanctions against North Korea.

Sens. Kirsten Gillibrand (D-N.Y.) and Susan Collins (R-Maine) filed an amendment that would prohibit the Pentagon from discharging troops because of gender identity and state that Congress believes qualified individuals should be able to serve, regardless of gender. The measure also requires Defense Secretary Jim Mattis to report the results of an ongoing study of transgender troops to Congress by the end of the year.

Sens. Cory Gardner (R-Colo.) and Edward J. Markey (D-Mass.) filed an amendment to excommunicate firms that do business with Pyongyang from the American financial system, as well as impose a full trade embargo on North Korean-made goods.

Both of those amendments directly challenge policies Trump has dictated over the past several weeks to mixed reviews. It is not clear, however, that congressional leaders were planning to allow the Senate to vote on such controversial policy amendments even before Paul issued his protest threat.

Senate Armed Services Committee Chairman John McCain (R-Ariz.), who does not routinely shy from criticizing Trump, noticeably has not offered to support any of the controversial policy measures that senators have expressed interest in attaching to the defense bill. McCain controls the defense bill in the Senate, a job that this year has extra significance following his recent announcement that he was diagnosed with brain cancer.

Last week, McCain suggested that the amendment put forth by Gillibrand and Collins was probably premature, because Mattis would not complete his planned review of serving transgender troops until Feb. 1. It is unclear whether the amendment's accelerated timetable, requiring Mattis to report to transgender troops by the end of the year, would build enough momentum to get McCain to change his mind.

McCain also declined to lend any encouragement to authors of amendments stiffening North Korea sanctions, saying he "may not even support" what they were proposing.

Corker, at the Senate Foreign Relations Committee, was more direct registering his disapproval, stating last week that the crisis with North Korea was too "acute" to contemplate moving "ahead with anything unless we do so in close conjunction with the White House."