The open letter from Republican senators warned that any nuclear deal could expire the day President Barack Obama 's term ends . Iranian diplomats confronted American counterparts twice at discussions Sunday and Monday in U.S. , a senior Switzerland official said . Secretary of State John Kerry and Iranian Foreign Minister Mohammad Javad Zarif to start several days of discussions . The Iranians have called the letter a propaganda ploy .
The open letter from Republican senators warned that any nuclear deal could expire the day President Barack Obama 's term ends . Iranian diplomats confronted American counterparts twice at discussions Sunday and Monday in Switzerland , a senior U.S. official said . Secretary of State John Kerry and Iranian Foreign Minister Mohammad Javad Zarif to start several days of discussions . The Iranians have called the letter a propaganda ploy .