PARIS (AP) -- French centrist presidential hopeful Emmanuel Macron has won the backing of Socialist former prime minister Manuel Valls, a high-profile yet embarrassing supporter for the independent candidate who tries to distance himself from the traditional political parties.
Valls said on BFM television Wednesday he will vote for Macron in the two-round presidential vote on April 23 and May 7 "because I think we must take no risk for the Republic".
He considers the centrist as the best candidate to face far-right leader Marine le Pen.
Valls' move is a further blow to the campaign of Socialist candidate Benoit Hamon.
Polls suggest Macron is the front-runner in the election and Hamon has no chance to advance to the runoff.
Macron thanked Valls for his support on Europe 1 radio, but said Valls wouldn't be part of his government if elected, because he wants to renew France's political elites.
Valls' decision is infuriating some Socialists, already deeply divided over the legacy of unpopular president Francois Hollande's term.
"Our candidate, after the primary and the unanimous (political) convention of the Socialists, is Benoit Hamon", the first secretary of the Socialist party Jean-Christophe Cambadelis wrote in a statement.
Valls, as a contender in the Socialist primary, had pledged to support the winner of the vote.
Former economy minister Arnaud Montebourg described him as a "man without honor" in a tweet.
Macron insisted Tuesday he wants to promote new figures in French politics, some of them coming from business and civil society.
"One backing counts as a vote... not an involvement in the campaign, not a change in our platform", he warned in a news conference.
The independent candidate is facing a series of challenges.
He has no party to rely on, wants to govern with personalities with no political experience, and if elected, needs a majority in France's lower house of parliament to be able to pass laws.
Parliamentary elections take place across France in June to choose lawmakers. Macron wants to present a candidate from his own movement, En Marche! (In Motion!), in every district.
He said he is convinced that if the French people choose him as president, they will also give him a majority at the National Assembly.