WASHINGTON — The White House says an open letter from Republicans to Iranian leaders interferes with negotiations over limiting Tehran’s nuclear ambitions. It says Republicans are advocating a rush to military action against Iran that is not in the best interests of the United States.

White House spokesman Josh Earnest says the letter from 47 Republican senators “throws sand in the gears” of the nuclear talks and is not the role that the Founding Fathers envisioned for Congress to play in foreign policy.

In the letter, Republicans said that without congressional approval, any deal between Iran and the U.S. would be merely an agreement between Obama and Iran’s supreme leader, Ayatollah Ali Khamenei.

Earnest said the letter was part of an “ongoing partisan strategy to undermine” Obama’s ability to conduct foreign policy.