Despite a burgeoning bromance and even a moment of dandruff diplomacy, Emmanuel Macron admitted Wednesday he had failed to persuade Donald Trump to stay in the 2015 nuclear deal with Iran, denouncing the administration’s U-turns on international agreements as “insane.”

His remarks, made to U.S. reporters before he left Washington Wednesday, were a concession that his charm offensive during this three-day trip to convince Trump to stay in the landmark deal had probably failed.

"My view – I don't know what your President will decide – is that he will get rid of this deal on his own, for domestic reasons," Macron said, adding there was a “big risk” Trump would scrap the deal.

Trump has long railed against the agreement, in which Iran agreed to accept restrictions on its nuclear activities in its exchange of the lifting of sanctions.

Citing the Paris climate change agreement, which Trump also pulled out of, Macron said such major policy reversals could “work in the short term, but it’s very insane in the medium to long term”.

The French leader had hoped to leverage his personal rapport with Trump to convince him to stick with the Iran deal, the hardwon result of tortuous diplomatic negotiations that was widely considered the international community’s best option to limit Tehran’s nuclear activities.

But their backslapping relationship did not stop him repeatedly taking aim at Trump’s isolationist stance during his visit. Earlier Wednesday, in a speech to Congress, Macron criticized the administration’s positions from international trade to climate change, and called on the U.S. to help “make our planet great again.”

“We can choose isolationism, withdrawal and nationalism,” he said. “But closing the door to the world will not stop the evolution of the world. It will not douse, but inflame the fears of our citizens.”

To applause from American lawmakers, especially the Democrats present, the French leader called on the U.S. to abandon its nationalist, America First impulses and instead embrace the more outward-looking approach of previous administrations.

“The United States is the one who invented this multilateralism. You are the one now who has to help preserve and reinvent it,” he said.

He added that he believed the U.S. would one day rejoin the Paris climate accord, calling the U.S.’s withdrawal a “short-term disagreement.”

“In the long run, we will have to face the same reality that we are citizens of the same planet.”

Trump has criticized the Iran deal for not addressing Iran’s missile program or its influential role in the Syrian conflict in support of the Assad regime. European signatories to the deal have looked to tackle those issues separately to the agreement.

Macron acknowledged the Iran deal was imperfect, but said it was the best option until a better agreement could be reached.

“It is true to say that this agreement may not address all concerns and very important concerns,” he said. “But we should not abandon it without having something more substantial instead. That’s my position.”