– The last time they met face to face, at the United Nations in September, French President Emmanuel Macron was puzzled when President Donald Trump and his delegation seemed to have no agenda, carried no papers and took no notes.

“It was like a good discussion with a buddy in a bar,” recalled a French official. “At the end, you don’t know exactly what it means.” Now that Trump has been in office longer, the official mused, “maybe the process is different.”

At the very least, the agenda will be clear when Macron arrives here Monday for the first official state visit Trump has hosted for any leader. Following their joint attack with Britain on Syria’s chemical weapons facilities this month, there is a Syria strategy to figure out. Trade, climate change, Russia, North Korea and counterterrorism are all on the to-do list.

But no issue looms larger than Iran and the nuclear agreement that the U.S. and five other countries signed with Tehran in 2015. Trump has called it a bad deal and said the U.S. will withdraw unless it is “fixed.” Signatories France, Britain and Germany vehemently disagree and have pledged they will not follow Trump’s lead.

The U.S. decision deadline is May 12. Failure to work out a compromise between the U.S. and its closest European allies that will keep the nuclear accord alive could lead to the most significant trans-Atlantic breach in decades.

Enter Macron. By consensus among his counterparts in Europe, if there is accommodation to be reached with Trump on Iran, he is the man to close the deal.

Senior French, British and German officials have been negotiating for months with a State Department team led by Brian Hook, director of policy planning, to come up with a way to meet Trump’s demands without altering the deal itself or driving the other signatories — Russia, China and, of course, Iran — to cry foul.

According to U.S. and European officials involved in those talks, significant progress has been made on addressing concerns about the deal’s sunset clauses, its verification rules, and the absence of restrictions on Iranian ballistic missile testing and development, as well as new measures to counter Iran’s “malign” activities in Syria and beyond in the Middle East. Four documents have been drafted that they believe are responsive to Trump’s criticisms.

An overall declaration and three subtexts are to outline their joint understanding that other international conventions will prohibit Iran from developing nuclear weapons beyond restrictions that expire in the next decade, push the International Atomic Energy Agency to expand its monitoring and promise strict sanctions if Iran moves forward with intercontinental ballistic missile development.

Mike Pompeo, Trump’s nominee for secretary of state, was a harsh critic of the deal when it was signed and spoke openly about bombing Iran’s nuclear installations. But at his confirmation hearing last week, Pompeo assured lawmakers that “there is no doubt that this administration’s policy, and my view, is that the solution to preventing Iran from getting nuclear weapons, to finding ourselves in the same place we are in North Korea in Iran, is through diplomacy.” He also agreed with the Europeans and the IAEA that Iran has so far complied with its terms.

Pompeo said, “I am confident that the issue will be discussed at great length” during Trump’s upcoming meetings with European leaders, including a one-day visit here by German Chancellor Angela Merkel on Friday following Macron’s departure Wednesday

Neither Macron nor the White House expect a final decision by Trump during the French president’s visit, officials from both countries said. For their part, the Europeans worry that the mercurial U.S. president, who railed against the deal during his presidential campaign and ever since, will ultimately decide to trash it even if his State Department recommends otherwise.

But Macron has been working toward this moment for months. “What I told him was not to tear up the deal,” he told journalists in October.

On Sunday, Macron told Fox News that there is no “Plan B” to the Iran deal.

“It’s a very long shot, but it’s the only one we have,” François Heisbourg, a former French presidential adviser on defense and national security, said of the Macron offensive. “You might as well try.”

The special bond that seems to have developed between the 71-year-old U.S. president and Macron, a 40-year-old political novice, is no accident. While Merkel is clearly turned off by Trump, and British Prime Minister Theresa May’s Parliament and population have indicated they don’t even want him to visit, Macron has gone far out of his way to cultivate him.

In addition to the September U.N. meeting, the two have near-weekly telephone conversations.

“It’s Macron’s nature,” said William Drozdiak, author of “Fractured Continent: Europe’s Crises and the Fate of the West” and an upcoming biography of the French president. “He walks into a room, sees a chair and tries to seduce it.”

Macron will address a joint session of Congress on Wednesday morning.