An influential US senator sought Thursday to revive a push for sanctions to curb Iran's nuclear ambitions, arguing that calling for new penalties is not war-mongering as suggested by the White House.

Sen. Robert Menendez, a Democrat, went on the offensive in a marathon floor speech outlining his distrust of the Iranian regime, saying he was "deeply skeptical" of Tehran's intention to adhere to an interim agreement with world powers over its nuclear program.

Menendez, chairman of the powerful Senate Foreign Relations Committee, is lead sponsor of a bill that would trigger sanctions if Iran walks away from the interim deal, which eases existing economic penalties in return for Tehran freezing its nuclear program.

"In my view, Iran's strategy, consistent with their past approaches that have brought them to a nuclear threshold state, is to use these negotiations to mothball its nuclear infrastructure program just long enough to undo the international sanctions regime," Menendez said.

Iran insists its nuclear drive is purely peaceful, but Menendez warned that it has refused to destroy any of its centrifuges, and was "weeks to months away from breakout" uranium enrichment capacity to produce a bomb should it ever resume the program.

"Let everyone understand: if there is no deal we won't have time to impose new sanctions before Iran could produce a nuclear weapon."

Menendez's legislation has support from 59 senators in the 100-member chamber.

But Obama has threatened a veto and several Democrats who favor the bill have since stepped back from a possible damaging vote against their own leader.

And Iranian officials have warned that new sanctions legislation could kill the negotiations.

Earlier in the day, 42 Republicans wrote to Senate Majority Leader Harry Reid, who controls the chamber's schedule, pressing for a vote.

But Menendez distanced himself from that tactic, saying "we cannot be pressured by a partisan letter into forcing a vote."

Menendez won plaudits from pro-Israel lobby AIPAC for his approach.

The New Jersey senator stood firm in refuting the White House argument that passage of his bill would amount to sabre rattling.

"It is a false choice to say a vote for sanctions is equivalent to war-mongering," Menendez said.