The American Israel Public Affairs Committee, which advocates pro-Israel policies to Congress and the White House, said it supported Senate Foreign Relations Committee Chairman Robert Menendez, D-N.J., co-author of the Senate sanctions bill, who suggested the GOP lawmakers' demand for a vote next week was turning a national security matter into a "partisan political issue."
"We agree with the chairman that stopping the Iranian nuclear program should rest on bipartisan support and that there should not be a vote at this time on the measure," AIPAC said in a statement.
"We have not and are not calling for [an] immediate vote," an AIPAC official told the Washington newspaper the Hill.
The New York Times said AIPAC previously pressured Senate Democrats to vote for the bill.
Menendez, who made his remarks about the sanctions vote in a Senate floor speech, did not explicitly call for a delay.
"I have long thought of this as a bipartisan national security issue, not a partisan political issue," he said. "And, at the end of the day, a national security issue that we must approach in a spirit of bipartisanship and unity, which has been the spirit for which we have worked together on this matter."
"I hope that we will not find ourselves in a partisan process trying to force a vote on a national security matter before its appropriate time."
His remarks came several hours after 42 of the 43 Republican co-sponsors of the sanctions bill wrote to Senate Majority Leader Harry Reid, D-Nev., demanding he schedule a vote on the measure next week.
None of the 16 Democrats who signed on to the bill signed the letter.
President Obama argues passing a sanctions bill now would doom talks aimed at preventing Iran from developing a nuclear weapon -- and put the United States on the road to another war.
He and other White House officials have urged senators to wait until after the six months of negotiations with Tehran play out.
Former President Bill Clinton added his voice to those urging no legislation at a private Senate Democratic retreat Wednesday night, the Washington publication Politico reported. Former Secretary of State Hillary Clinton has also sided with Obama on the matter.
Reid lashed out at the Republicans who wrote the letter to him Thursday.
"It's not a partisan issue -- it's a serious, serious situation," Reid said in remarks quoted by Politico. "For me to receive a totally partisan letter, we should not make this a partisan issue, and that's what 42 Republicans have done. And I think it's wrong."
Reid wouldn't respond when asked if he would schedule the sanctions measure for a vote before the negotiations conclude.
On Monday, 70 House Democrats sent a letter to Obama backing his diplomatic efforts and opposing new sanctions.