LAUSANNE, Switzerland - A defiant letter from Senate Republicans to Iran's leaders is complicating international negotiations to end a 12-year international impasse by imposing strict limits on Iran's nuclear program in exchange for easing economic sanctions.
As U.S. and Iranian officials began a weeklong push to complete the outline of an agreement, Tehran repeatedly demanded an explanation of the letter written by freshman Sen. Tom Cotton, R-Ark., and signed by 47 of the 54 Republican senators, a senior Obama administration official said.
The open letter, released last week, warned Iranian leaders that any accord reached by President Obama without congressional approval could be voided "with the stroke of a pen" by a future president, and that future Congresses could modify the agreement "at any time" if lawmakers consider it too lenient.
Iranian officials raised the letter in a negotiating session Sunday, and again Monday, according to the administration official. The two sides met behind closed doors for five hours in a luxury hotel here.
"These kinds of distractions are not helpful when we're talking about something so serious," said the official, who declined to be identified under administration ground rules.
The official declined to say how U.S. officials responded, or provide other details. The official said the contentious issue didn't stop the two sides from trying to resolve other differences still under negotiation two weeks before a self-imposed deadline.
Appearing Sunday on CNN, Senate Majority Leader Mitch McConnell of Kentucky defended the letter and warned that the administration is negotiating a "very bad" nuclear deal. Cotton said he had no regrets about the letter, saying the fierce criticism it sparked showed that President Obama wasn't negotiating "the hardest deal possible."
Secretary of State John Kerry met with Iranian Foreign Minister Mohammad Javad Zarif here Monday after separate talks by senior diplomats and technical experts Sunday.