Deputy Secretary of State Tony Blinken declined Wednesday to say whether Congress should have the ability to vote up or down on a potential nuclear agreement with Iran, emphasizing that the Obama administration fears any action taken by lawmakers could cause the fragile talks to collapse.

“I think you’ll also understand the position of the administration, for that matter any administration, Republican or Democrat, on the importance of maintaining the executive prerogative to conclude agreements that advance our national security interests and do not require formal congressional approval,” Blinken told the Senate Foreign Relations Committee. “There’s concern that this could set a precedent for future executive branch action.”

The committee held the hearing to determine the possible role of Congress in ongoing nuclear negotiations between the U.S. and five world powers with Iran on that country’s nuclear program.

“We’re trying to find a constructive way for Congress to play its rightful role in these negotiations,” said Chairman Bob Corker, R-Tenn. “I’m very disappointed that, in essence, what the administration is saying is that we really don’t want — even though Congress put us in this place — we really don’t want Congress to play a role in one of the most important geopolitical agreements that may take place during this administration.”

Blinken said the administration fears that any steps from Congress could alienate the other international partners in the negotiations. Corker objected to the suggestion, saying he had spoken with many of the negotiating partners and none opposed Congress taking any action in ongoing talks to ensure the deal reached is a good one.

Tony Blinken

Jacquelyn Martin/AP

“I have met no one who believes that us weighing in would do anything to destabilize these negotiations. And, as a matter of fact, many have said knowing that Congress has to approve the deal would be a great backstop for the administration to strengthen their hand, just as the negotiators in Iran continue to refer to the hardliners and to [Supreme Leader Ayatollah Ali] Khamenei,” Corker said.

The chairman has proposed measures that would give Congress an up-or-down vote on a deal reached by the world powers and Iran. The Senate Banking Committee, which is responsible for additional sanctions legislation, postponed its hearings on Iran until next week. That committee is considering legislation proposed by Sen. Mark Kirk, R-Ill., and Robert Menendez, D-N.J., that would impose additional sanctions on Iran if the talks fall apart.

President Barack Obama reiterated Tuesday night in his State of the Union address that he would veto any legislation passed by Congress that would impose additional sanctions.

“There are no guarantees that negotiations will succeed, and I keep all options on the table to prevent a nuclear Iran,” Obama said. “But new sanctions passed by this Congress, at this moment in time, will all but guarantee that diplomacy fails — alienating America from its allies and ensuring that Iran starts up its nuclear program again.”

Obama said last week the chance that the process will succeed is “less than 50/50.”

Negotiations between Iran and the six major powers failed to reach a deal by a November deadline and have been extended in hope of crafting the framework of an agreement by March. The specifics of any such agreement would need to be finalized by the end of June.

Blinken declined to get into specifics about where negotiations stand on several key issues because it could jeopardize the process, but he said the administration would be happy to conduct a classified briefing for lawmakers.

Several senators at the hearing acknowledged that initial concerns the Joint Plan of Action, the document governing the terms of the negotiations, would cause the current sanctions regime to completely collapse have proven unfounded.

But Sen. Marco Rubio, R-Fla., used the Obama administration’s recent Cuba policy changes as evidence for why Congress was wary of ongoing nuclear negotiations with Iran.

Rubio, who is Cuban-American, said Blinken had promised in his confirmation hearing before the committee that he would consult with members on any actions to be taken on Cuba. Rubio, Corker and Menendez, who is also Cuban-American, said they were not consulted on the diplomatic renewal Obama announced in December. Rubio and Menendez both vocally oppose the new policies.