(CNN) For all of President Donald Trump's obvious affection for nationalist autocrats, the first leader he formally welcomed to Washington, on Monday ahead of Tuesday night's state dinner, was the leader of the French Republic, the free and fairly elected internationalist Emmanuel Macron.

Trump and Macron, who was elected in May 2017, share one of the most examined relationships in world politics. At a glance, they would appear to have little in common, ideologically or temperamentally. But over the course of nearly a year on the same global stage, the pair have emerged as remarkably close personal allies.

Unlike with the prospect of Brexit, another European thunderclap, Trump took no early liking to Macron's candidacy, instead indicating his preference for the French centrist's election runoff opponent, far-right National Front leader Marine Le Pen. But after a few tense meetings, marked in public by their bizarrely protracted -- and definitely "not innocent" -- handshake in Brussels, Macron seems to have secured what his European counterparts could not: a personal bond with the US President.

"There's a strong rapport on the anti-jihadist war and that will continue because France, of course, is at the core of this, both on its territory and in the Middle East," said Philippe Le Corre, a former French government official who's now a senior fellow at Harvard's Kennedy School. "And Trump -- to him, it's very important. He thinks there are terrorists everywhere, even with relatively few attacks in the US compared to Europe."

But this isn't simply a marriage of mutual interests. Macron and Trump are at odds over most of the most pressing issues they are expected to discuss during the visit. For the next few days, Macron is expected to lobby Trump to, among other things, reverse his expected course and abide by the Iran nuclear deal, maintain the US presence in Syria, tamp down tariff threats and -- albeit a long shot -- re-enter the Paris climate agreement.

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