US President Donald Trump on Friday refused to certify the nuclear deal with Iran, effectively sending the decision to Congress on whether the US will impose sanctions on Iran and thus withdraw from the international agreement.

Congress now has 60 days to decide if it will reimpose sanctions lifted under the agreement that had been signed in 2015 in exchange for Tehran dismantling its nuclear program. It's still unclear how the House of Representatives and Senate will move forward — and there is a chance lawmakers will decide not to put new sanctions on Iran or that efforts to reimpose sanctions will not gather enough votes to go into effect.

But this is what US politicians are currently considering.

Read more: What is the Iran nuclear deal?

While many Republicans, who control both legislative chambers, previously voted against US participation in the deal, several conservative lawmakers have warned of dire consequences of a complete US withdrawal.

'Trigger points' and 'sunset' provisions

Republican lawmaker Ed Royce, chairman of the House Foreign Affairs Committee, told a congressional hearing on Wednesday that the US should continue to adhere to the deal despite the administration's reservations. "As flawed as the deal is, I believe we must now enforce the hell out of it," he said.

His colleague, US Senator Bob Corker, who serves as chairman of the Senate Foreign Relations Committee, said he intended to introduce "trigger points" to the Iran Nuclear Agreement Review Act, a US law that gives Congress the right to review issues related to Iran's nuclear program and the international deal. The "trigger points" would allow sanctions to go into effect if Iran fails to comply on certain key issues.

Read more: Trump and the Iran nuclear deal: A crisis in the making

Corker's proposal also includes "indefinitely" restricting the accord's "sunset" provisions that would allow Iran to gradually advance its uranium enrichment program as of 2025.

"We have provided a route to overcome deficiencies and to keep the administration in the deal, and actually make it the kind of deal it should have been in the first place," said Corker.

However, not all Republicans are on the same page. Florida Senator Marco Rubio voiced support for the president's decision in a statement but also expressed skepticism about the Corker plan, and said he would prefer a clean pullout from the international deal. 

"Ultimately, leaving the nuclear deal, reimposing suspended sanctions, and having the president impose additional sanctions would serve our national interest better than a decertified deal that leaves sanctions suspended or a new law that leaves major flaws in that agreement in place," the senator said.

Republicans are also unlikely to find much support among their Democratic Party colleagues in Congress who tended to support maintaining the deal with Iran.

In a tweet, Democratic leader Nancy Pelosi called Trump's decision a "grave mistake."

Top Senate Democrat Chuck Schumer seconded his colleague's criticism, and said Trump should listen to his presidential advisers who have recommended sticking with the nuclear deal. 

And Ben Cardin, the ranking Democratic Senator on the Foreign Relations Committee, insisted he would support congressional measures that also earned the backing of the European allies who had signed the nuclear deal.

How such sentiments across the political aisle will play out in Congress will be seen over the next two months.

cmb, ls/cmk (AFP, AFP)