Republican lawmakers can do little to block or significantly alter the final nuclear agreement with Iran, despite blistering criticism and a pledge from at least one GOP hawk that it is dead on arrival.

The deal is neither a treaty nor a trade agreement that requires congressional signoff, and it does not appear to have funding implications that would allow lawmakers to assert their power of the purse to slow-roll or stall implementation.

Under the Iran Nuclear Review Act (PL 114-17), Congress has 60 days to review the agreement and can hold a potential vote of approval or disapproval sometime this fall, which could ultimately be one of the most high-profile national security votes in recent memory.

Senate Foreign Relations Chairman Bob Corker, who authored the legislation, said Tuesday he was deeply skeptical the deal would prevent Iran from obtaining a nuclear weapon.

“Congress will need to scrutinize this deal and answer whether implementing the agreement is worth dismantling our painstakingly-constructed sanctions regime,” the Tennessee Republican said.

Republican hawks intent on undoing the agreement are banking on the Iran vote — their best chance to influence, at least politically, the implementation of the deal — taking place sometime in the fall.

“Over the coming weeks, I will work tirelessly to protect America from this deal and to stop Iran from obtaining nuclear-weapons capability,” said Arkansas Sen. Tom Cotton, perhaps the most vocal and persistent critic of the Iran talks. “I am confident that the American people will repudiate this dangerous deal and Congress will kill the deal.”

But President Barack Obama, who has said he welcomes debate on and congressional oversight of the deal, has already threatened to veto any efforts to block the agreement.

“This deal demonstrates that American diplomacy can bring about real and meaningful change,” the president said in early morning remarks at the White House. “Because America negotiated from a position of strength and principle, we have stopped the spread of nuclear weapons in this region.”

If Republicans somehow cobble together a two-thirds majority in both chambers to overcome a veto of the resolution of disapproval, the president would lose his waiver authority to lift the statutory sanctions. Only his authority to lift the less powerful executive sanctions would remain in place.

But on one of the most significant security achievements of his presidency, Obama will likely have enough support from members of his own party to thwart GOP efforts to kill the agreement.

“This agreement won’t need much, if anything, from Congress,” said Steve Vladeck, a law professor at American University’s Washington College of Law. “So we’re going to get a whole lot of sound and fury from the legislature that will ultimately signify nothing, barring some real shift in the politics of this.”

Nonetheless, the vote could provide interesting political theater on a worldwide stage, sending a negative message about the strength of the deal if Obama must resort to his veto pen.

“It does cast a pall over the whole thing,” said Jeremy Rabkin at George Mason University.

Mark Dubowitz at the Foundation for Defense of Democracies said a vote of disapproval would be a major political defeat for the president — and could set the stage for tweaking the deal down the road.

“While it wouldn’t stop the deal from going forward initially, it would lay the political predicate for the next president and the next Congress to take some significant steps to toughen the implementation of the deal, to renegotiate the fundamental terms of the deal, and to begin to build a new Iran policy in 2017,” Dubowitz said.

Dubowitz, who believes the Iran vote will be the most politically consequential vote since the Iraq War authorization in 2002, suggested it will be a tough one for Democrats.

“If you vote yes for a deal that ends up failing in all of the ways the critics have been suggesting, then it’s your name on a deal that ends up being a national security disaster,” he said.

Still, Republicans have a steep climb ahead if they have any hope of killing the agreement, which was two years in the making and has garnered cautiously positive reaction from many congressional Democrats, most of whom are reserving public endorsement until they have time to review the details.

“I have to think, from the administration’s perspective, this agreement was crafted in a way to be as Congress-proof as possible,” Vladeck said. “Congress has the bully pulpit, but not actually the bully stick.”

Rachel Oswald contributed to this report.