House Republicans and Democrats vented frustration with the White House and urged it to get tougher in talks with Iran over its nuclear program on Wednesday, as the administration launched a full-court press to persuade lawmakers to allow more time for negotiations.

Members of the House Committee on Foreign Affairs expressed skepticism over a potential short-term deal that would offer limited, temporary sanctions relief to Iran in exchange for Tehran freezing elements of its nuclear-energy program.

Secretary of State John Kerry spent the weekend in Geneva in tense negotiations with Iran, but the talks failed to produce a deal. The fragile negotiations are set to resume Nov. 20.

In the interim, Obama administration officials are getting an earful from lawmakers nervous that the U.S. is already conceding too much to Iran.

Committee on Foreign Affairs Chairman Ed Royce, R-Calif., warned against any easing of sanctions against Iran as part of any interim agreement unless Tehran agrees to stop enriching uranium completely. Instead, he said, Congress should pass a new round of sanctions to heighten pressure on Iran and compel it to make “meaningful and lasting” concessions.

“The Iranian regime hasn’t paused its nuclear program, why should we pause our sanctions efforts, as the administration is pressuring Congress to do?” he asked Wednesday during the hearing on the status of talks with Iran.

“Only when the Iranian regime is forced to decide between economic collapse or compromise on its rush to develop a nuclear weapons capability, do we have a chance to avoid that terrible outcome,” he added.

Echoing those sentiments, Ranking Member Eliot Engel, D-N.Y., said the U.S. must make it “crystal clear” to Iran that they “must stop enriching, period.”

He also admonished the Obama administration for failing to keep Congress fully informed about the status of the negotiations.

The administration has defended its approach and Wednesday pressed Congress not to impose additional sanctions, arguing that negotiations are in a fragile period and diplomacy needs more time.

Vice President Joe Biden will join Kerry in meetings with their former Senate colleagues to ask them to hold off on a new sanctions package.

Sen. Lindsey Graham, R-S.C., said he believes new sanctions would likely help more than harm negotiations. But he stressed that the real issue is Iran’s continued enrichment of uranium.

“They are telling us they have a red line on enrichment,” he said. “Well, I have a red line on enrichment. Why would anybody in their right mind allow the Iranians an enrichment capability given their 30-year history of mayhem throughout the world? In Mexico, in Canada, with their nuclear programs, there is no enrichment."

“There is no entitlement to enrichment,” he added.

While most lawmakers and the administration agree that any deal with Iran would require some sanctions relief, they differ on the way to approach it.

The loose framework of a preliminary deal began leaking even before Kerry arrived last week in Geneva, prompting Israeli Prime Minister Benjamin Netanyahu to voice deep concerns and label it the “deal of the century” for Iran.

Over the weekend, French Foreign Minister Laurent Fabius also took a jab at the Obama administration, warning it not to engage in a “fool’s game.”

Under the deal’s blueprint, if Iran drops its level of enrichment from 20 percent to 3 percent, the U.S. would lift some sanctions for a six-month period while it confirms Tehran’s compliance. But the U.S. would keep the most severe sanctions in place until Iran addresses international fears that it is trying to develop nuclear-weapons capability.

Royce said the initial sanctions relief under discussion would allow Iran to recoup as much as $50 billion in frozen oil assets if it begins the process and complained about reports that the Obama administration already began softening sanctions after the election of new Iranian President Hassan Rouhani in June.

He said he was particularly concerned that the proposed deal “failed to adequately address” Iran’s heavy water reactor, allowing the government to continue enriching uranium and even “continue building centrifuges.”

Colin Kahl, an Iran expert and associate professor at Georgetown University, testified that the figure was closer to $10 billion in assets and said it was important to have a preliminary agreement to “buy time” to allow more extensive negotiations.

Kahl also warned Congress not to ratchet up sanctions at such a sensitive time, saying it will only hurt the outcome if “we start to look like the unreasonable party.”

But without new sanctions, Mark Dubowitz, an Iran sanctions expert with the conservative Foundation for Defense of Democracies, said the U.S. is at its “high-water mark of negotiating leverage” with Iran.

The danger of reducing sanctions before seeing verifiable concessions from Iran, he said, is “we may find ourselves in six-month’s time back in Geneva and we may have undermined our leverage.”

David M. Drucker contributed to this story.