French President Emmanuel Macron urged U.S. lawmakers Wednesday to ensure that the United States does not to abandon the deal to restrain Iran's nuclear weapons development.
"Iran shall never possess nuclear weapons, not in five years, not in 10 years, never," Macron declared in a ringing 49-minute speech to both chambers of Congress.
The French leader did not directly address U.S. President Donald Trump's vocal opposition to the 2015 pact.
Trump is set to decide next month whether to renew sanctions relief for Iran. The agreement lifts sanctions on Tehran in exchange for limits on the country's nuclear development.
The U.S. president called the agreement "insane" and "ridiculous" and has threatened to withdraw from it.
WATCH: Macron on Iran nuclear deal
Instead Macron, as he did in talks with Trump on Tuesday, called for negotiations for a new agreement with Iran over its ballistic missile tests and its military involvement in Syria, Yemen, Lebanon and Iraq.
Lawmakers cheered robustly as Macron praised America's history of multilateralism, saying Europe and the United States must together face the "new threats and challenges" of the 21st century.
"We can choose isolationism, but it will not stop the evolution of the world," he said. Western allies cannot let nationalistic impulses take over and "undermine the liberal order we set after World War II. It is a critical moment."
"I thought on balance his speech was right on target and he had the courage not to trim on issues which he thought were important," House Minority Whip Steny Hoyer, a Maryland Democrat, told reporters shortly after the speech.
Representative Chris Collins, a Republican from New York and the first member of Congress to endorse Trump in 2016, told VOA he saw Macron's comments as a positive step in addressing the problems with the Iran nuclear deal.
"Now that we've got France saying, 'Yeah, we can negotiate a better deal,' I think that's in response to Trump's position," Collins said.
But Iranian President Hassan Rouhani on Wednesday rejected the idea of a new deal or any changes in the current pact negotiated by the Obama administration and Britain, Germany, Russia, China and France.
Trump stands alone among the signatories to the Iran deal in opposing it.
The French president also pressed lawmakers to support a return to the Paris climate agreement, saying "there is no Planet B."
Trump withdrew from the accord in 2015, following an intense effort by the Obama administration to strike the sweeping agreement.
"I'm sure one day the U.S. will come back again to join the Paris agreement," Macron predicted.
The French leader delivered his speech on the final day of a three-day visit to Washington, the first state visit of Trump's presidency.