Wary of Iran's nuclear intentions, senators are predicting a bipartisan push for fresh penalties and increased leverage against Tehran despite administration opposition, and waiting to hear directly from Secretary of State John Kerry about the latest round of talks that failed to produce a deal.
Kerry tried to reassure skeptical members of Congress after negotiations in Geneva between Iran and Western powers stalled, with France turning down a list of demands on Iran, saying they were too generous to mean an easing of international sanctions.
"Some of the most serious and capable expert people in our government who have spent a lifetime dealing both with Iran, as well as with nuclear weapons and nuclear armament and proliferation, are engaged in our negotiation. We are not blind, and I don't think we're stupid," Kerry told NBC's "Meet the Press."
He added: "We're not going into a full deal and giving away something. We're talking about stopping their program where it is, with enough guarantees to know that it is, in fact, stopped where it is, while we then negotiate the full measure of the deal with our allies."
Administration officials led by Vice President Joe Biden and including Kerry had persuaded a number of senators late last month to delay consideration of a new round of penalties before the international talks had begun.
Sen. Bob Corker, R-Tenn., said the Senate's Democratic leadership had called off a Senate Banking, Housing and Urban Affairs Committee session this coming week to examine proposed sanctions, and that Kerry would be on Capitol Hill to brief lawmakers about Iran.
"I do know that on both sides of the Capitol, on both sides of the aisle right now, people are really looking at what the next steps ought to be," Corker told NBC.
"All of us want to see diplomacy. We do. And we thank the secretary for the efforts that he's putting forth. That is the best way to resolve this issue. But we're also concerned about an administration that seems really ready always to jump into the arms of folks and potentially deal away some of the leverage we have."
Corker said new penalties would not kick in for several months, and that the current sanctions could be toned down, if necessary, based on Iran's actions.
"I think this week sitting down, talking with Secretary Kerry is going to be an important element of what we do. ... We know the sanctions have gotten us here, and we're worried we're dealing away with our leverage."
Sen. Bob Menendez, chairman of the Senate Foreign Relations Committee who has repeatedly sponsored tough sanctions legislation, spoke of "the possibility of moving ahead with new sanctions, including wording it in such a way that if there is a deal that is acceptable, that those sanctions could cease upon such a deal."
He told ABC's "This Week" that "it's an insurance for the United States to make sure that Iran actually complies with an agreement that we would want to see."
At the same time, he said, it would be an incentive for the Iranians "to know what's coming if you don't strike a deal."
Sen. Lindsey Graham, R-S.C., said sanctions have brought Iran to the negotiating table and "if we back off now, I think that's exactly the wrong signal."
He told CNN's "State of the Union" that "a new round of sanctions will be coming from the Congress. The Congress will define the end game because we're worried about the end game, not some interim deal. You can't trust the Iranians."
In the broader region, he said, "the Israelis are apoplectic about what we're doing. I've never been more worried about the Obama administration's approach to the Mideast then I am now."
A top Kerry deputy, Wendy Sherman, arrived Sunday in Jerusalem for a one-day visit for consultations on Iran, the State Department said.
Obama has said that if Iran halts advances and reverses parts of its nuclear program, the United States would offer "modest relief" to ease the economic squeeze on Tehran.
But he told NBC in an interview last week that core sanctions would remain and that if Iran's leaders back out of a deal "we can crank that dial back up." Such measures include penalties that have crippled Tehran's oil exports.