Se. Rand Paul (R-Ky.) questions state insurance commissioners during a hearing on the individual health insurance market for 2018 on Capitol Hill last week. (AP) (Manuel Balce Ceneta/AP)

The Senate will vote Wednesday on an amendment aimed at forcing Congress to debate and vote on a replacement authorization for military force within six months, after Sen. Rand Paul threatened to hold up the entire defense bill until the measure was scheduled.

The scheduled vote, which is expected to take place before lunch, according to Senate Majority Leader Mitch McConnell's (R-Ky.) office, is a victory for Paul (R-Ky.), who promised Monday night to stage a one-man protest if necessary to force a debate about the military's various combat operations against extremist groups, including in Afghanistan, America's longest-running war.

But Paul may not be victorious in the outcome, after several senators who support drafting a new AUMF spoke against Paul's effort to set a high-stakes deadline.

Sen. Jeff Flake (R-Ariz.), who is one of the two leading senators writing and promoting a new AUMF for fighting extremist groups, said Tuesday that he could not support Paul's amendment "because of the very real risk associated with repealing such a vital law before we have something to replace it with."

The ranking Democrat on the Senate Armed Services Committee, Sen. Jack Reed (R.I.), also warned about the message Paul's amendment might send to the world about the country's commitment to foreign conflicts in which it is already involved.

"The headlines in Baghdad and the headlines in Kabul and the headlines in Damascus would be 'U.S. moves to end engagement,'‚ÄČ" Reed said. "Unless we could do something literally next week, we would be running into the reality of American military commanders wondering whether they should begin to plan for the extraction of our forces."

One week is an unlikely turnaround in a Senate that has been musing about an AUMF for years. The pattern of talking about passing an AUMF, but with minimal action, frustrated Sen. Tim Kaine (D-Va.) to the point Tuesday of announcing he would support Paul's efforts, despite criticizing his strategy earlier.

"I view his amendment as an attempt to force Congress to do what it should do," Kaine said. "I think it is way past time, way past time, for Congress to take this up and for everybody to be on the record."

Sen. Tammy Duckworth (D-Ill.), a veteran of the Iraq War, also announced Tuesday that she would support Paul's measure.

But for most of the day, Paul and his new allies had yet to persuade Senate Armed Services Committee Chairman John McCain (R-Ariz.) to put the measure on the floor.

McCain controls the procedural decisions for the annual defense bill's progress through the Senate, and has been wary of committing his support to any controversial amendments that might complicate the legislation. Thus far, support for the defense bill has been reliably bipartisan.

Compared to years past, many senators have also been rather restrained in pushing McCain to take on the kind of policy fights that could directly challenge the Trump administration. McCain has never been shy about criticizing the president, but he is very protective of the defense bill, which Congress has passed each of the last 55 years. Once the measure gets through the Senate, there is still a looming battle coming with the House, which has its own version of the defense bill. And though McCain is committed to that task, he will be taking it on while undergoing regular treatment for brain cancer at the National Institutes of Health.

In a preliminary deal Monday night, McCain granted Paul four hours to take the floor and speak his piece about the defense bill. Paul showed up to work on Tuesday looking like he might be planning to stand for far longer than that, wearing army green chinos and comfortable-looking shoes that stuck out against the Senate's traditional sea of formal suits and wingtips.

He would ultimately use only about 27 minutes of his allotted time.

When the Senate does vote on Paul's amendment Wednesday, it is expected to be a motion to table the amendment. If the vote is successful, it will kill's Paul's effort, leaving senators to sort out next steps.

Kaine and Flake are expected to keep pressing for their AUMF proposal in the Senate Foreign Relations Committee, of which Paul is a member and where Chairman Bob Corker (R-Tenn.) has promised them a vote. Their proposal would replace the 2001 AUMF that Congress passed to authorize the war in Afghanistan with a new measure authorizing military action against al-Qaeda, the Islamic State and the Taliban.

In the meantime, Corker did not object to a vote on Paul's amendment.