GOP lawmakers seek to codify Trump's Iran sanctions amid ongoing nuclear talks

A new bill from a pair of Republican lawmakers would prevent the Biden administration from lifting key sanctions on Iran over the country's alleged support of efforts to assassinate high-profile Americans and critics on U.S. soil.

The bill, set to be introduced Wednesday by Iowa Sen. Joni Ernst and Florida Rep. Mike Waltz, would codify Trump-era sanctions imposed on Iran -- specifically, on major industries and financial institutions -- according to legislative text shared first with ABC News.

Should the U.S. and its allies reach an agreement with Iran in ongoing negotiations to return to the 2015 nuclear agreement reached under President Barack Obama, the PUNISH Act would prevent the Biden administration from lifting the Trump sanctions -- and unfreezing billions of dollars in Iranian assets -- until the State Department can certify that Iran has not supported efforts to kill prominent American citizens or Iranian dissidents on American soil for five years.

While the Democratic majorities in the House and Senate aren't expected to consider the proposal, it signals Republicans' intent to pressure and constrain Biden's foreign policy agenda and negotiations with Iran should they retake control of either chamber of Congress in the November elections.

"President Biden should not provide a dime of sanctions relief to the largest state sponsor of terrorism, which is actively trying to kill U.S. officials and citizens, at home and abroad," Ernst will say Wednesday, according to prepared remarks shared with ABC News.

In August, an alleged Iranian operative with links to the country's Revolutionary Guard Corps was charged by the Justice Department in what prosecutors called a plot to murder Trump's former national security adviser John Bolton. The Justice Department accused the Iranian government of supporting the assassination attempt in response to the 2020 U.S. missile killing of military leader Qasem Soleimani. (Iran has claimed the case is "baseless" and politically motivated.)

Bolton and several top Trump administration officials, including former Secretary of State Mike Pompeo and former Defense Secretary Mark Esper still receive government protection due to ongoing threats from Iran, sources familiar with arrangements told ABC News.

The U.S. government has said Iran encouraged attacks on author Salman Rushdie, who was stabbed in August at a public event in upstate New York. (Iran denied involvement.) And in July, a federal court unsealed an indictment charging four Iranian nationals with conspiring to kidnap an outspoken Iranian American activist and journalist in Brooklyn.

It's against this backdrop that Republicans say they must try to limit the White House's ability to change sanctions without assurances of nonviolence.

"Whether you want to argue whether it's a return to the [2015 nuclear agreement] or a new deal, it astounds me that we are continuing to negotiate with a regime with active plots against American officials … that is instigating attacks on Americans citizens," Waltz told ABC News.

Republicans and some Democrats have questioned the Biden administration's efforts to reenter the Obama-era deal to curb Iran's nuclear program after the Trump administration withdrew from the agreement in 2018 and slapped on sanctions as part of a "maximum pressure campaign." Iran responded by enriching more uranium at higher levels beyond the limits of the deal.

Biden's critics have expressed concerns that Iran can still develop its nuclear program in secret while using newly unfrozen assets and oil revenue to support terrorist proxies and other groups across the Middle East that threaten U.S. interests and allies.

Last year, a bipartisan group of 140 U.S. lawmakers urged Biden to reach a "comprehensive" deal with Iran to limit its nuclear program and address other national security issues.

In an interview with CBS News that aired Sunday, Iranian President Ebrahim Raisi denied his country's involvement in the alleged attempt against Bolton and said American pledges to abide by a new nuclear deal would be "meaningless" without a "guarantee" that the U.S. would not withdraw from a future deal and reimpose economic sanctions on Iran.

Raisi, who is now in New York for the U.N. General Assembly and is scheduled to address the gathering on Wednesday, met with French President Emmanuel Macron on Tuesday amid a stalemate in indirect negotiations over the return to a nuclear agreement.

Both sides have exchanged proposals in recent weeks, but they publicly remain at odds over a U.N nuclear watchdog investigation and Iran's insistence on a guarantee that the U.S. would not pull out of any deal.

Republican efforts to codify sanctions on Iran are "designed to tie this president or future presidents' hands so he or she cannot waive these sanctions to encourage better Iranian behavior and bring Iran's nuclear behavior under a modicum of control," Daryl G. Kimball, the executive director of the Arms Control Association, who has called for a return to the nuclear agreement, told ABC News.

Waltz, the lead author of the bill in the House, told ABC News that he thinks Iran "is constantly holding out because they believe they can get a better deal." Waltz argued that if the country's leaders "see these things codified by Congress, and they see clear action by the Congress, then that puts them in a weaker negotiation position."

ABC News' Luke Barr contributed to this report.