Legislation granting Congress the power to review a nuclear deal with Iran is facing a life-or-death moment in the Senate.

Republican Leader Mitch McConnell (Ky.) is seeking an agreement to allow votes on several controversial amendments backed by conservatives that supporters of the bill say would kill it.

To buy more time, McConnell pushed off a planned Monday night vote on a separate labor bill to consult with other Republicans. The full conference is expected to talk about the Iran bill at their Tuesday lunch.

{mosads}The majority leader has preferred not to pick sides in fights that divide his conference, opting to let his colleagues hash things out and move toward consensus.

Yet on the dicey Iran issue, some Republicans predicted McConnell may have no choice but to file cloture to end debate on the Iran measure and avoid voting on amendments that could kill the bill.

While this could anger conservatives, it would also save a carefully crafted compromise drawn up by Senate Foreign Relations Committee Chairman Bob Corker (R-Tenn.) and reluctantly endorsed by the White House.

“I think that’s his only option. I know he doesn’t want to do it. I don’t want him to do it, but it seems to me we could be dragging this out for days and weeks,” Sen. John McCain (R-Ariz.) said Monday evening.

McConnell was blindsided late last week when Sens. Tom Cotton (R-Ark.) and Marco Rubio (R-Fla.) set up a series of votes on controversial amendments to the Iran bill, including one that would require Iran to recognize Israel’s right to exist as part of any final nuclear deal.

Democrats have warned that if Rubio’s amendment comes up for a vote, it will likely pass — derailing the broader bill.

Senior Democratic aides say McConnell cannot expect Democrats to shoulder the dangerous burden of a killing a pro-Israel amendment.

Its passage could also endanger the nuclear talks, which are set to continue until a June 30 final deadline. The Obama administration says requiring Iran to recognize Israel would throw a monkey wrench in the negotiations.  

The GOP leader on Monday night decided against filing cloture to end debate on the underlying Iran bill, which would have prevented a vote on Rubio’s measure.

Democrats had expected McConnell to move Monday to end debate. Instead, McConnell stuck to his pledge — at least for the time being — to allow robust debates on the Senate floor and plenty of votes on amendments.

Senate Republican Whip John Cornyn (R-Texas) said McConnell is trying to reach an agreement on amendments with members of his own caucus as well as Democrats.

He said he cannot imagine Democrats agreeing to a vote on Rubio’s amendment.

Corker said Monday he expects McConnell to move to end debate and block the possibility of additional votes on amendments “fairly soon.”

Walking out of McConnell’s office Monday evening, Corker said he had a “very good meeting” and predicted “we’re going to finish the bill this week.”

Rubio said Monday that he did not speak with McConnell over the weekend and reiterated his desire to get a vote on his proposal while acknowledging that his leader may not have that flexibility.

“I want to get a vote on my amendment but I understand the process,” he said.

McConnell can’t delay a vote on Iran indefinitely given the crowded Senate schedule.

The Senate must pass legislation to extend the solvency of the Highway Trust Fund and surveillance authority for the National Security Agency by the end of the month.

McConnell also wants to pass fast-track trade authority before the Memorial Day recess. 

“He doesn’t have the luxury of time on this one,” a senior Democratic aide said of the Iran bill.

McConnell reiterated his pledge to allow free-flowing floor debates just last week, when he said of the Iran bill, “we ought to have a full and open and robust amendment process, and I believe that’s what we’ll have.”

McConnell last month avoided a potential fight within his conference over whether to restore the 60-vote threshold to end debate on controversial nominees by helping to round up more than 60 votes to advance Loretta Lynch, who was nominated for attorney general, to a final vote.  

Jordain Carney contributed.