U.S. Secretary of State John Kerry, left, listens to Iran's Foreign Minister Mohammad Javad Zarif, right, before resuming talks over Iran's nuclear program in Lausanne, Switzerland, Monday, March 16, 2015. The United States and Iran are plunging back into negotiations in a bid to end a decades-long standoff that has raised the specter of an Iranian nuclear arsenal, a new atomic arms race in the Middle East and even a U.S. or Israeli military intervention. (AP Photo/Brian Snyder, Pool)
The Associated Press
LAUSANNE, Switzerland (AP) - A senior U.S. official says Iranian negotiators confronted their American counterparts about a letter from Senate Republicans warning that any nuclear agreement could expire the day President Barack Obama leaves office.
The official says the letter came up in nuclear talks Sunday between senior U.S. and Iranian diplomats. It was raised again in discussions Monday led by Secretary of State John Kerry and Iranian Foreign Minister Mohammad Javad Zarif.
The official wouldn't characterize Iran's position. But both Iranian and U.S. officials have criticized the letter written by freshman Sen. Tom Cotton of Arkansas and signed by 46 fellow GOP senators.
Kerry has said several times that the letter undermines U.S. diplomatic efforts and falsely claims Congress can change an executive agreement.
The official wasn't authorized to speak publicly on the matter and briefed reporters only on condition of anonymity.
U.S. Secretary of State John Kerry, right, rides his bicycle along the shore of Lake Geneva, after holding meetings with Iran's Foreign Minister Javad Zarif over Iran's nuclear program, in Lausanne, Switzerland, Monday, March 16, 2015. The United States and Iran are plunging back into negotiations in an effort to end a decades-long standoff that has raised the specter of an Iranian nuclear arsenal, a new atomic arms race in the Middle East and even a U.S. or Israeli military intervention. (AP Photo/Brian Snyder, Pool)
The Associated Press
U.S. Secretary of State John Kerry takes a break during a bilateral meeting with Iranian Foreign Minister Mohammad Javad Zarif over Iran's nuclear program in Lausanne, Switzerland, Monday, March 16, 2015. The United States and Iran are plunging back into negotiations in an effort to end a decades-long standoff that has raised the specter of an Iranian nuclear arsenal, a new atomic arms race in the Middle East and even a U.S. or Israeli military intervention. (AP Photo/Keystone, Jean-Christophe Bott)
The Associated Press
U.S. Energy Secretary Ernest Moniz, U.S. Secretary of State John Kerry, Iran's Foreign Minister Mohammad Javad Zarif and the head of the Atomic Energy Organization of Iran Ali Akbar Salehi, from left to right, pose for a photograph before resuming talks over Iran's nuclear program in Lausanne, Switzerland, Monday, March 16, 2015. The United States and Iran are plunging back into negotiations in a bid to end a decades-long standoff that has raised the specter of an Iranian nuclear arsenal, a new atomic arms race in the Middle East and even a U.S. or Israeli military intervention. (AP Photo/Brian Snyder, Pool)
The Associated Press
U.S. Secretary of State John Kerry, left, and Iran's Foreign Minister Mohammad Javad Zarif, right, pose for a photograph before resuming talks over Iran's nuclear program in Lausanne, Switzerland, Monday, March 16, 2015. The United States and Iran are plunging back into negotiations in a bid to end a decades-long standoff that has raised the specter of an Iranian nuclear arsenal, a new atomic arms race in the Middle East and even a U.S. or Israeli military intervention. (AP Photo/Brian Snyder, Pool)
The Associated Press
Iran's parliament speaker Ali Larijani listens to a question during a press conference at parliament in Tehran, Iran, Monday, March 16, 2015. Referring to the Iran's nuclear talks with world powers, Ali Larijani told reporters on Monday that a final nuclear deal can serve interests of both Iran and the region. (AP Photo/Vahid Salemi)
The Associated Press