Criticism from Democrats and Republicans was so intense that a key State Department official was left fumbling for a defense of statements last month from President Obama and top White House aides.

“I don’t think any of you … are war mongers,” said Wendy Sherman, undersecretary of state for political affairs.

Obama last month said new economic sanctions would “sabotage” the talks because Iranian representatives would walk out of the negotiations. White House spokesman Jay Carney has accused supporters of new sanctions of leading a “march to war,” and Bernadette Meehan, a spokeswoman at the National Security Council, used similar inflammatory language against members of Congress.

At a Senate Foreign Relations Committee hearing Tuesday, committee chairman Robert Menendez criticized the administration for failing to understand that supporters of more sanctions are pursuing a tactic to strengthen the hand of U.S. negotiators. But, the New Jersey Democrat, added the White House is confusing “tactics with war-mongering and fear-mongering.”

He noted that a senior Iranian official bragged recently that the “iceberg of sanctions is melting,” calling the statement an indication that Iran is using the talks to weaken Western punitive measures.

“At the end of the day, Iran cannot be a nuclear threshold nation,” he said.

Sen. Bob Corker of Tennessee, the senior Republican on the committee, said, “I am disappointed in the rhetoric from the administration … Unfortunate things have been said.”

He also questioned whether the six-month talks that began last month will reduce Iran’s capability to develop a nuclear weapon.

“They have reached a threshold. They can build a bomb,” he said.

Sherman tried to defend deal under which Iran agreed to halt parts of its nuclear program in exchange for some relief from international sanctions that, according to administration officials, have crippled Iran’s economy and increased domestic pressure on the brutal theocratic regime.

She argued for time for negotiators to push Iran into a permanent agreement to stop enriching nuclear fuel and abandon any plans for nuclear weapons. Sherman also argued against further sanctions during the six-month talks.

The House has already passed new sanctions, and Senate supporters of tougher measures are close to gathering enough strength to override Obama’s threat of a veto.

Sherman also tried to soothe Senate fears that the administration will accept a bad deal with Iran that would allow it to preserve its current nuclear program.

“Nothing is agreed until everything is agreed,” she said.

Menendez noted that the sanctions bill he is sponsoring would take effect only if the talks with Iran fail. Corker criticized the Iran deal for failing to curtail its ballistic missile program.

“Why would you negotiate a deal that keeps that in place?” he asked.

Sherman responded that a missile program without a nuclear warhead would be “almost irrelevant.”

Sen. Chris Coons, a Delaware Democrat, questioned Iran’s commitment to any final deal that would come out of the interim talks.

“This is a regime we cannot trust,” he said.

Sen. Tim Kaine, a Virginia Democrat, said he supports the administration’s diplomatic efforts but warned that he would endorse military actions against Iran if the talks fail.

“If there is no other way, I’m going to vote, ‘Yes,'” he said.

Sen. James E. Risch, an Idaho Republican, angrily dismissed the negotiations.

“This thing is a disaster …. I’ve been disgusted by it,” he said.

Risch also pressed Sherman for news about Saeed Abedini, an Iranian-American pastor from his state who has been held in Iran since July 2012.

“His only crime is being a Christian,” he said.

Abedini is one of three American citizens jailed in Iran. Robert Levinson, a former CIA employee, disappeared in Iran seven years ago, and Amir Hekmati, an ex-Marine accused of spying, was arrested in July 2011.

Sherman assured him that Secretary of State John F. Kerry raises the issue of the imprisoned Americans regularly with top Iranian officials.

Several senators questioned whether Western corporations are rushing to win contracts with Iran and undermining the remaining sanctions.

David S. Cohen, undersecretary for terrorism and financing at the Treasury Department, said any Western firm seeking long-term business with Iran is wasting its time. The sanctions relief amounts to about $7 billion and opens limited access to Iran’s oil and energy sector for only six months. He tried to reassure the committee that the remaining sanctions continue to punish Iran for its nuclear program, support for terrorism and abuse of human rights.

“Iran is not open for business,” he said.