Robert Menendez FILE
Washington CNN  — 

Sen. Bob Menendez promised Tuesday to hold off his support for additional sanctions against Iran until after the initial negotiations deadline.

Menendez, the lead Democratic sponsor of the Nuclear Free Iran Act, announced Tuesday during a Senate Banking Committee hearing on Iran that he sent a letter to President Barack Obama vowing – alongside nine other Democrats – not to vote for his own sanctions bill until after the March 24 deadline. Menendez will still help steer his bill through the banking committee on Thursday.

The move essentially killed any chance of passing the sanctions bill before negotiators’ deadline to reach a framework agreement, let alone of reaching a majority to surpass the veto Obama has promised to deliver. The news came just a week after Menendez accused the administration of peddling talking points “straight out of Tehran.”

Two other Democratic members of the Senate Banking Committee, Sen. Jon Tester and Sen. Chuck Schumer, another key Democratic sanctions supporter, joined Menendez and the six other senators in promising the President not to vote on the sanctions bill until after the March deadline.

Schumer said during the hearing Tuesday that he would vote to approve the bill in the banking committee on Thursday to key it up for a full vote if no agreement is in sight.

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Sen. Bob Corker, chairman of the Seante Foreign Relations Committee, said it’s unlikely the Senate will vote on a sanctions bill with Menendez and key Democrats pulling back.

“If we want to speak with one voice and show strength to Iran it’s likely that we’re not going to vote on the Senate floor on sanctions until after March 24,” said Corker, a Republican from Tennessee.

Instead, Corker is focused on gathering support for his own bill, which would allow Congress to weigh in on a final deal.

Deputy Secretary of State Tony Blinken said Menendez’s decision to pull back recognizes that negotiators “could use the time and space effectively.”

He said it answers “a big problem that we had” and stressed that Congress and the administration need to present a united front to the world and Iran as negotiators look to seal a deal.

The U.S., Iran and the five other negotiating partners have set a final deadline for July, but administration officials testifying on Tuesday would not guarantee that a deal will be reached in time.

“If we get to June and we have the core elements of a deal in place and we’re working on the technical details and it turns out we need a little more time to dot all Is and cross all the Ts, we may seek it,” Blinken said Tuesday.

Responding to a question from hawk Sen. Tom Cotton, a Republican from Arkansas, Blinken emphasized that the administration was prepared to walk away from negotiations and reimpose sanctions if it’s clear in March that Iran is not moving toward agreeing to a deal that would curb its nuclear program.

“If we come to the conclusion … that they’re simply not going to get to yes, that they can’t do it or they won’t do it,” Blinken said.

Blinken continued to emphasize the “real risk” a sanctions bill would present to the fate of negotiations.

Instead of looking for every way to weigh in with legislation now, Blinken said the Senate should wait until the administration needs to ask Congress to roll back the sanctions currently in place.

Despite pledging to hold off on a “yes” vote for his own sanctions bill, Menendez still used his questioning time to deliver a fiery denunciation of Iran’s willingness to ultimately drop its nuclear weapons ambitions and its attempts to sidestep current restrictions to advance its nuclear program.

Menendez didn’t even leave time for Blinken to respond, though Blinken asked to address Menendez’s concerns, asserting that the administration is also concerned about Iran’s true motives and has fought back vigorously against Iranian “cheating.”

Menendez worked with Sen. Mark Kirk, the lead Republican sponsor of the sanctions bill, to recraft the legislation in an effort to attract additional Democratic support.

And it appears he was able to win some support from some of those Democrats on the fence about supporting sanctions legislation. In the letter to Obama, the Democratic senators call themselves “supporters” of the latest Kirk-Menendez bill and vow to vote for the bill after the March deadline “if Iran fails to reach agreement on a political framework that addresses all parameters of a comprehensive agreement.”

Menendez won over the support of Sens. Richard Blumenthal, Chris Coons and Joe Manchin, for example, who supported Kirk-Menendez last year but retracted their support after the bill died.