British Prime Minister Theresa May and her team appealed to President Trump in an 11th-hour bid to convince him not to take a step away from the Iran nuclear deal, according to United Kingdom officials.

May called Trump, while British Foreign Minister Boris Johnson reached Secretary of State Rex Tillerson to discourage the president from making an expected announcement that he believes the Iran deal is not in the national security interests of the U.S. The issue is one of the chief policy disagreements between May and Trump, who often have projected more of an affinity than Trump shows for other European leaders.

"The nuclear deal was a crucial agreement that neutralized [Iran's] nuclear threat," Johnson said in a statement released Tuesday evening after his call with Tillerson. "The UK supports the deal and stresses the importance of all parties continuing to uphold their commitments."

May's team made a similar argument to Trump."[May] reaffirmed the UK's strong commitment to the deal alongside our European partners, saying it was vitally important for regional security," according to a readout of the phone call. "The [prime minister] stressed that it was important that the deal was carefully monitored and properly enforced."

European officials — chiefly in the U.K., France, and Germany — have been making that case in private for months, without apparent success, and more recently in public. The British team beat the American side to the punch on Tuesday, releasing summaries of the conversations in advance of Trump administration readouts. But it's hardly clear that they persuaded the administration.

"Trump spoke today with [May] to address ways to deny Iran all paths to a nuclear weapon," the White House said in a readout of the phone call, released hours after the U.K. summary. "President Trump underscored the need to work together to hold the Iranian regime accountable for its malign and destabilizing activities, especially its sponsorship of terrorism and its development of threatening missiles."

That's an apparent allusion to Trump's belief that the Iran deal does not do enough to curb the regime's aggression in the Middle East. He is expected to announce that the deal is not in U.S. interests, but delay imposing the sanctions waived as part of the deal in order to create leverage for forcing Iran to agree to new restrictions on their nuclear and ballistic missile programs.

European leaders fear that such a move will lead to the collapse of the deal. They argue that the pact at least "neutralizes" the threat of an Iranian nuclear weapon, but American opponents of the deal believe it leaves the regime with a dangerously robust nuclear program while permitting the funding for an aggressive effort to dominate the Middle East.

"[Trump] can't be sure [Iran is] complying because they won't give access to certain critical military sites," Sen. Tom Cotton, R-Ark., told the Washington Examiner in a recent interview. "Even if they were complying with every single letter, word, and spirit of the JCPOA, it's still not in our national security interests. We've seen them run wild over the last two years."

Trump has to make an announcement before Oct. 15, by federal law. "There are signed policies on Iran," White House national security advisor H.R. McMaster said Tuesday, "which you will hear about more this week."