The Senate Foreign Relations Committee grilled President Biden’s nominee for the No. 2 position at the State Department on Wednesday, homing in on her role as the chief negotiator for the 2015 Iran nuclear deal during the Obama administration.

The nominee for deputy secretary of state, Wendy Sherman, faces a difficult confirmation process as Republicans and some Democrats raise concerns about the Biden administration’s promise to reenter the deal, even as some liberal groups say the White House is moving too slowly on restoring an agreement that President Donald Trump abandoned.

The debate comes as the Biden administration’s diplomacy on Iran has stalled. The European Union has proposed a meeting with the Iran deal’s original participants, but Tehran has balked at the idea because of Biden’s decision to maintain Trump’s “maximum pressure” sanctions. Meanwhile, U.S. personnel in Iraq have continued to come under rocket fire by militia groups, some of which have ties to Iran.

Sherman sought to placate hawkish lawmakers by vowing to seek a new agreement with Iran that lengthens and strengthens the accord, and by sparsely defending the original deal.

“I remain clear-eyed about the threat that Iran poses to our interests and those of our allies,” Sherman said. “I would note that 2021 is not 2015, when the deal was agreed, nor 2016, when it was implemented. The facts on the ground have changed, the geopolitics of the region have changed, and the way forward must similarly change.”

The top Republican on the committee, Sen. James E. Risch of Idaho, said for him “rejoining the old nuclear accord is a non-starter” and told her he was deeply disappointed in “your performance” in negotiating the deal.

Sen. Marco Rubio (R-Fla.) probed Sherman on any contacts she had with Iranian officials during the Trump administration.

Sherman noted that she met with Foreign Minister Mohammad Javad Zarif and other Iranian officials on the sidelines of the Munich Security Conference and had urged Iran not to violate the nuclear deal. She said she coordinated those conversations with the Trump administration’s undersecretary of state for political affairs.

In 2015, Iran sharply curtailed its nuclear program in exchange for sanctions relief from the world powers that forged the deal: the United States, Russia, China, France, Germany and Britain. The International Atomic Energy Agency has said Iran maintained those constraints until the Trump administration pulled out of the deal in 2018.

The decision by Sherman and other Biden officials to pledge to get a better deal, rather than defending the Obama accord on its own merits, has frustrated some on the left.

Sen. Chris Murphy (D-Conn.) said by seeking to expand the deal rather than restore the agreement, “I worry we may be setting ourselves up for failure.”

Liberal groups echoed that sentiment in a letter addressed to Biden on Wednesday demanding that he follow through on his promise to “quickly” rejoin the deal and end the Trump-era policies of crippling economic sanctions.

“The longer the elements of ‘maximum pressure’ remain in effect, the more it will continue to embolden hardliners and make U.S.-Iran diplomacy more difficult,” said the groups, including MoveOn, J Street and Win Without War. “The recent escalation in military activity between the United States and reported Iranian proxies in Syria and Iraq only shows how urgently needed a new course of action is.”

Republicans repeatedly voiced concerns about lifting sanctions on Iran, given its support for militia groups and its ballistic missile arsenal. Sherman promised to voice those concerns to her superiors if confirmed for the position, a conciliatory posture that raised some concerns among liberals.

“I hope this is just a confirmation tactic, but Sherman refuses to defend the Iran Deal she negotiated,” tweeted Joe Cirincione, the former president of Ploughshares, a group that supported the deal. “Is Biden folding?” he added. “What’s his plan? All this very discouraging to Biden allies.”

Sherman’s approach resulted in a cordial atmosphere at the hearing, though none of the Republicans indicated they would support her confirmation in the closely divided Senate.

Risch acknowledged that Sherman would largely be following the orders of the Biden White House and suggested that would be an improvement over the Obama administration. “You are carrying water for different people this time than you were last time,” he said.

He praised her comments recognizing that events had changed since the deal was reached.

“Your comments about this not being 2015 are greatly appreciated,” he said.