A pair of Republican senators unveiled a plan Friday to sanction Iran if the regime gets close to constructing a nuclear weapon, as part of a President Trump's broader effort to counter Iranian aggression.

Under the proposal, Iran would face "automatic" economic sanctions if it builds up its nuclear program to the point of being within one year of having a bomb. The plan was developed by Senate Foreign Relations Chairman Bob Corker, R-Tenn., and Sen. Tom Cotton, R-Ark., one of the arch critics of the Iran deal. The one-year time frame is designed to ensure that Iran doesn't get so close to having a nuclear weapon that the United States can't take action to prevent it.

"Iran knows that their economy remains fragile, and crippling, embargo-like sanctions would probably run the clock on regime stability faster than they could get to nuclear breakout," Cotton told the Washington Examiner during a recent interview, without mentioning his specific legislation.

Corker and Cotton wrote the legislation in order to reinforce Trump's determination that the nuclear agreement negotiated by former President Obama's team, known formally as the Joint Comprehensive Plan of Action, is not in the national interest of the United States. Trump on Friday was expected to announce that he won't immediately impose the sanctions that Obama waived under the agreement in order to leave the door open for negotiating improvements to the deal.

"The legislation would not conflict with the JCPOA upon passage," a fact sheet from the Senate emphasized. "Instead, it would set conditions that halt Iran's nuclear program and provide a window of time for firm diplomacy and pressure to work."

The Corker-Cotton bill is an apparent effort to deprive Iran of the leverage it seems to have under the deal as currently written. Critics have long complained that the deal was front loaded to give the regime a financial windfall, raising the likelihood that Trump's effort to improve the deal would result in Iran pocketing the money they've already received and then continuing to develop a nuclear weapons program.

Their bill also represents an answer to congressional Democrats who doubted that Congress could take effective action to improve the agreement. "Congress has a role to play in foreign policy, but we cannot pass a law to unilaterally change an international agreement," New York Rep. Eliot Engel, the top Democrat on the Foreign Affairs Committee, said Thursday.

Corker and Cotton believe that the bill, if passed, would prevent Iran from developing a dangerous nuclear program without technically violating the deal. Opponents of the agreement have argued that the pact allows the regime to expand their nuclear program gradually before the expiration or "sunsetting" of the agreement — a threat the senators hope to avert.

"The legislation automatically re-imposes sanctions if Iran's nuclear program violates certain restrictions," the fact sheet said. "These restrictions remain in force indefinitely, effectively ridding the JCPOA of its sunset provisions as they apply to U.S. sanctions; bolster IAEA verification powers; and limit Iran's advanced centrifuge program."

If Iran triggers those U.S. sanctions, Cotton expects that the regime would be locked out of the European market, as well, even if European countries wanted to continue trading with Iran.

"Our allies in Europe and Asia at that point can decide whether they would like to do business with the largest economy in the world ... or a terror-sponsoring country's economy that's approximately the size of the Maryland's economy," Cotton told the Washington Examiner in September. "I think that's a pretty easy choice for foreign leaders."