WASHINGTON -- A controversial Iran sanctions bill is losing steam in the Senate, where at least three of its own Democratic cosponsors are warning that pushing the legislation now could thwart delicate international negotiations.

"Now is not the time for a vote on the Iran sanctions bill," Sen. Chris Coons (D-Del.) said at a Wednesday event hosted by Politico.

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Sen. Kirsten Gillibrand (D-N.Y.), a cosponsor of the sanctions bill, said in a statement to HuffPost on Wednesday, “After speaking with the President, I am comfortable giving him the additional time requested before this bill goes to the floor."

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Sen. Joe Manchin (D-W.Va.) echoed those sentiments Tuesday night.

"I did not sign it with the intention that it would ever be voted upon or used upon while we were negotiating," Manchin said on MSNBC. "I signed it because I wanted to make sure the president had a hammer if he needed it and showed them how determined we were to do it and use it if we had to."

He added that it’s better to "give peace a chance."

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Sen. Richard Blumenthal (D-Conn.) already said earlier this month that a vote on the bill was not needed during the interim agreement.

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Meanwhile, a spokeswoman for Sen. Ben Cardin (D-Md.) punted the matter to Reid.
"Senator Cardin wants to see negotiations with Iran succeed. As for timing of the bill, it is and has always been up to the Majority Leader," Cardin spokeswoman Sue Walitsky said.

Both of the bill’s main sponsors, Sens. Mark Kirk (R-Ill.) and Robert Menendez (D-N.J.), held their ground when asked for their reactions to Obama’s veto threat.

“While the president promises to veto any new Iran sanctions legislation, the Iranians have already vetoed any dismantlement of their nuclear infrastructure,” Kirk said in a statement.

On Tuesday night, just after the State of the Union had ended, Menendez said, "I’m not frustrated." He walked quickly into an elevator as he spoke, pushing the buttons and looking ready to be done with the conversation. "The president has every right to do what he wants."