European allies negotiating with the United States on how to fix the Iran nuclear deal are running out of time to convince President Trump to remain in the agreement, according to U.S. officials and administration allies.

“This is a last chance,” a State Department spokesperson told the Washington Examiner. “In the absence of a commitment from our European allies to work with us to fix the deal’s flaws, the United States will not again waive sanctions in order to stay in the Iran nuclear deal.”

On its face, that statement simply reiterates President Trump’s previous warning that he will renew the sanctions waived by then-President Barack Obama if Congress and European allies fail to take a tougher posture regarding the Joint Comprehensive Plan of Action, as the deal is formally entitled. The final deadline is in May.

But the pointed reminder comes as a senior State Department official is in the midst of a trip to Europe for negotiations that administration allies believe could determine Trump’s ultimate decision to remain or withdraw from the agreement.

“There has to be a finite time frame in terms of evaluating whether you keep the Iran deal,” a House Republican lawmaker familiar with the administration’s thinking told the Washington Examiner. “I think the Europeans will need to show that they're negotiating in good faith.”

That raises the stakes for State Department Director of Policy Planning Brian Hook, who is leading a U.S. delegation to Europe this week. Hook met Thursday in Berlin with representatives from the United Kingdom, France, and Germany (known collectively as the E3) and will spend Friday in Vienna, Austria, for a meeting of the JCPOA Joint Commission meeting. That summit will be attended by the E3 as well as the remaining parties to the JCPOA — the European Union, China, Russia, and Iran.

“The deal’s greatest flaw is that its restrictions sunset over time, leaving Iran free in the future to pursue industrial scale nuclear fuel enrichment, an important step in achieving a rapid nuclear weapons breakout capability,” the State Department spokesperson said.

That’s a major sticking point in the talks with the Europeans, who worry that U.S. efforts to place additional restrictions on Iran could amount to a unilateral attempt to reverse the concessions made during the JCPOA talks.

"What we're wanting to do is come up with a package across the board of European and U.S. cooperation to achieve our joint goals,” one European diplomat told the Washington Examiner. "The redline from the European side is that we will not rewrite the JCPOA."

The meetings take place in the immediate context of Trump’s decision to fire Secretary of State Rex Tillerson, who favored remaining in the deal, and replace him with the more-hawkish CIA Director Mike Pompeo. Most see that as a sign the Trump administration will take an even tougher stance as the clock ticks down.

"He stands to give the U.S. additional credibility to the option of nixing the deal, because he had talked about how this deal is a bad deal quite a bit,” Behnam Ben Taleblu, a research fellow at the Foundation for the Defense of Democracies, told the Washington Examiner.

If the negotiating teams can’t break the impasse, Trump’s hostility to the Iran deal could harden quickly into a decision to scrap it. “Negotiations are fragile, so I don't know that it's make or break,” the House lawmaker said. “I do know that if they're sticking hard and fast to their position that that imperils the deal, it doesn't promote it.”

As the State Department spokesperson emphasized: “The president was clear that he approved the issuance of sanctions waivers in January only in order to give us time to secure our European allies’ agreement to fix the JCPOAs terrible flaws . . . And if at any time the president judges that agreement is not within reach, the United States will withdraw from the deal immediately.”