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Eric Risberg, Associated Press
In this photo taken July 16, 2015, Republican presidential candidate, former Florida Gov. Jeb Bush speaks to reporters in San Francisco. Unhappy with President Barack Obama’s nuclear deal with Iran? The solution is as simple as putting a Republican in the White House, according to GOP candidates who have vowed to rescind the agreement, some on their first day in office.

WASHINGTON — Republicans running for the White House have vowed to rescind President Barack Obama's nuclear deal with Iran. But actually revoking it may not be that easy.

If Iran lives up to its obligations, a new president could face big obstacles in turning that popular GOP campaign promise into U.S. policy. Foreign policy experts say the hurdles would include resistance from longtime American allies, an unraveling of the carefully crafted international sanctions, and damage to U.S. standing with the rest of the world.

Both Obama and Republicans know firsthand the difficulties of dismantling major policies, a task that only gets harder the longer a policy has been in place.