“Special interests and donors” being Obama code for Jews.

Washington (CNN) – A heated exchanged between President Barack Obama and Sen. Robert Menendez (D-New Jersey) broke out Thursday over whether the U.S. should impose new sanctions on Iran amid ongoing negotiations over the country’s nuclear program, according to two senators who were in the room.

Menendez, the leading Democrat pushing for additional sanctions against Iran, forcefully pressed Obama on the need for additional sanctions during a meeting in which Obama urged Menendez and other senators to drop their efforts to pass sanctions legislation. Additional sanctions, Obama argued, could torpedo ongoing negotiations over Iran’s nuclear program.

The unusually sharp exchange, between a senior senator and a president from his own party, occurred during a Senate Democratic retreat at a hotel in Baltimore. A senior administration official also confirmed details of the exchange, which was first reported by the New York Times.

Obama said that as a former senator himself, he understood how outside forces — like special interests and donors — can influence senators to act, one of the senators recounted.

That’s when Menendez stood up to challenge the President, telling Obama he took “personal offense” to his assertions, the New York Times reported, arguing that he has worked to curb Iran’s nuclear ambitions for many years and was not motivated by political considerations.