WASHINGTON (Reuters) - US Senate Republican leader Mitch McConnell said on Sunday that President Barack Obama was on the verge of making a "very bad deal" on Iran's nuclear programme and made clear that Congress will weigh in on any agreement.
"Apparently the administration is on the cusp of entering into a very bad deal with one of the worst regimes in the world that would allow them to continue to have their nuclear infrastructure," McConnell said on CNN's "State of the Union" programme.
"We're alarmed about it."
US Secretary of State John Kerry was resuming negotiations with the Iranians in Lausanne, Switzerland, on Sunday with the goal of reaching a framework agreement by the end of March and a final accord by June 30.
Kerry said on Saturday he hoped "in the next days" it would be possible to reach an interim deal.
As negotiations between world powers and Iran intensified this month, opposition to the agreement in the works erupted in the US Congress. An open letter sent last week to Iran's leaders from 47 Republicans in the 100-member Senate warned that any nuclear deal reached with Obama may be undone after he leaves office in 2017.
The letter was denounced by the White House and the State Department as interference into international negotiations.
On Saturday, the White House warned Republican senators that proposed legislation requiring Congress to approve any accord reached with Iran over its nuclear capabilities could have a "profoundly negative impact" on negotiations.
The letter from White House Chief of Staff Dennis McDonough was the latest sign of rising tension between the White House and Republicans.
McConnell said the Democratic president "clearly doesn't want Congress involved in it - at all. And we're worried about it."
He said if a deal is reached with Iran, the Senate would vote on a bill that would require the deal to come to Congress. Obama has said he would veto such a measure.
If no deal is reached, McConnell said, lawmakers will consider a bill that would ratchet up sanctions against Iran.
Some Senate Democrats also want a congressional review. "I have supported the negotiations to this point but any deal that touches upon the congressional statutory sanctions is going to get a review of Congress," said Senator Tim Kaine of Virginia.
"The only question is, are you going to have a constructive deliberate bipartisan process, or are you going be rushed and partisan?"