France's top diplomat is leaving his post to become chief of the Constitutional Council, France's top court which makes sure that legislation complies with the constitution.

French President Francois Hollande formally proposed the nomination of Laurent Fabius to the Constitutional Council in a statement Wednesday. Fabius, 69, had been in office since 2012.

"I led the French diplomacy with pride and I served it with pleasure", Fabius told lawmakers at France's lower house of parliament, the National Assembly, getting loud applause.

His successor was not named immediately, but a government reshuffle is expected in the coming days. Environment and Energy Minister Segolene Royal and former Prime Minister Jean-Marc Ayrault are widely considered as front-runners to take the position.

Fabius told iTele television his one regret as foreign minister is that "the world didn't follow" France's position on Syria. Paris pushed the U.S. to join in a military intervention during the summer of 2013.

"We should have taken action," he said.

In his speech at the National Assembly, Fabius denounced the "terrifying brutality" of Syrian President Bashar Assad's regime. "There is, we ought to say, and I call the ones responsible by their name, a complicity of Russia and Iran," he said, and called for a cease-fire in Syria.

Fabius represented France in the nuclear negotiations with Iran, and for years he worked to help revive Israeli-Palestinian peace talks, as a strong supporter of the "two-state solution."

His international stature soared in December, when almost 200 countries reached an agreement at the U.N. climate conference in Paris. Fabius was praised for his patience and listening skills, and received a standing ovation when he gaveled the deal.

"It's rare in life to be able to move things forward at the planet level," a visibly moved Fabius said.