WASHINGTON — Republican lawmakers warned the leaders of Iran on Monday that any nuclear deal they cut with President Barack Obama could expire the day he leaves office. The White House denounced the GOP’s latest effort to undercut the international negotiations as a “rush to war.”

Monday’s open letter from 47 GOP senators marked an unusually public and aggressive attempt to undermine Obama and five world powers as negotiators try to strike an initial deal by the end of March to limit Iran’s nuclear programs.

Republicans say a deal would be insufficient and unenforceable, and they have made a series of proposals to undercut or block it — from requiring Senate say-so on any agreement to ordering new penalty sanctions against Iran or even making a pre-emptive declaration of war.

Obama, noting that some in Iran also want no part of any deal, said: “I think it’s somewhat ironic that some members of Congress want to make common cause with the hard-liners in Iran. It’s an unusual coalition.”

The letter was written by freshman Sen. Tom Cotton of Arkansas, who opposes negotiations with Iran. It’s addressed to the “Leaders of the Islamic Republic of Iran” and presents itself as a constitutional primer to the government of an American adversary. Senate Majority Leader Mitch McConnell of Kentucky’s signature is on it, as are those of several prospective presidential candidates.

Explaining the difference between a Senate-ratified treaty and a mere agreement between Obama and Iran’s Ayatollah Ali Khamenei, the senators warned, “The next president could revoke such an executive agreement with the stroke of a pen, and future Congresses could modify the terms of the agreement at any time.”

Iranian Foreign Minister Mohammed Javad Zarif responded via state media, dismissing the letter as a “propaganda ploy” and noting that many international deals are “mere executive agreements.” He suggested the senators were undermining not only the prospective deal with Iran but other international agreements as well.