WASHINGTON — Before Congress had even begun its official review, Republican leaders vowed Tuesday to kill President Obama’s nuclear accord with Iran, setting up a fierce fight to save the president’s signature diplomatic achievement.

Congress will have 60 days to review the deal, once all documents have been sent to the Capitol, after which it can pass a resolution of approval, pass one of disapproval or do nothing. Mr. Obama would veto a resolution of disapproval, and the opponents could derail the agreement only if they could rally the required two-thirds vote of Congress to override his action.

“I want to go through this process and make sure we fully understand what we’re voting on,” said Senator Bob Corker, Republican of Tennessee and chairman of the Senate Foreign Relations Committee. “In the end, those who believe this truly is going to keep Iran from getting a nuclear weapon will vote for it. Those who believe that is not the case, and the world is not going to be safer — in some ways it may pave the way for them to get a nuclear weapon — will vote against it.”

Mr. Corker, the chief author of the review act, strongly implied that he was in the latter camp.

Republican opposition to diplomatic overtures dates at least to President Richard M. Nixon’s visit to China. Even President Ronald Reagan faced a backlash after raising the prospects of deep nuclear arms reductions after meeting Mikhail S. Gorbachev in Reykjavik, Iceland.