Former Secretary of State John Kerry has fielded dozens of private meetings and phone calls in recent months in an effort to preserve the Iran nuclear deal, as President Trump appears poised to withdraw from the pact.

The Boston Globe reported on Friday that Kerry, who helped broker the 2015 nuclear agreement, met with Iranian Foreign Minister Mohammad Javad Zarif at the United Nations in New York last month to discuss ways to salvage the Joint Comprehensive Plan of Action (JCPOA) - the formal name for the Iran deal.

He has also met and spoken with a handful of European officials. Last month, he met with German President Frank-Walter Steinmeier, according to the Globe, and spoke by phone with Federica Mogherini, the European Union's top foreign affairs official.

Kerry also reportedly met with French President Emmanuel Macron, both in New York and in Paris.

During a recent state visit to Washington, Macron lobbied Trump to stay in the Iran deal.

The former secretary of State under President Obama has also, at times, joined forces with former Energy Secretary Ernest Moniz to try to rally support for the JCPOA among members of Congress, including Speaker Paul Ryan (R-Wis.), the Globe reported.

The Iran deal was hailed by the Obama administration as a landmark accomplishment that helped curb the potential nuclear threat posed by Tehran by limiting its ability to refine uranium and produce nuclear weapons.

But Trump has long railed against the pact, calling it "one of the worst deals I have ever witnessed."

In October, he disavowed the deal, but stopped short of withdrawing from it entirely. Instead, he demanded that negotiators work to fix what he has deemed as holes in the agreement.

He faces a May 12 deadline to determine whether he will pull out of the pact, and despite efforts by European leaders to convince him to remain in the deal, Trump appears likely to withdraw, congressional and foreign leaders have said.