PARIS (Reuters) - French Socialist presidential hopeful Manuel Valls distanced himself from his main rival for his party’s presidential ticket on Friday and left open the door to backing centrist independent Emmanuel Macron instead.

A combination picture shows French Socialist party politicians, former prime minister Manuel Valls (L) and former education minister Benoit Hamon, candidates in the second round for the French left's presidential primary election, as they attend the first prime-time televised debate in La Plaine Saint-Denis, near Paris, France, January 12, 2017. Picture taken January 12, 2017. REUTERS/Philippe Wojazer

The former prime minister, who is from the right wing of his party, made the comment on BFM TV ahead of a head-to-head vote in a primary on Sunday in which his leftwing rival Benoit Hamon is favorite to beat him to become the official Socialist candidate.

His comment follows talk that some of Valls backers in parliament are preparing to throw their weight behind Macron, a centrist whose pro-business policies are close to those of Valls, if the more traditionalist Hamon wins.

“I will take a back seat,” Valls said when asked what he would do if he loses on Sunday.

“I am at the heart of the progressive movement - from Hamon to Macron, because we have to bring it together,” he added.

The term ‘progressive’ is used in France to define a grouping that is left of center but not necessarily socialist in nature.

Opinion polls show Macron is firmly in third place in the race for the Elysee and offers an alternative between the Left and the Right to the two main frontrunners, conservative Francois Fillon and far-right leader Marine Le Pen.

Macron was a minister with Valls in President Francois Hollande’s Socialist government until he quit last year to launch his presidential campaign.

But he was not a party member, and has spurned the Socialist primaries that Valls and Hamon are contesting, having launched his own centrist political movement last summer.

The polls show the ruling Socialists have little chance of winning the presidency, regardless of who is their candidate.

However, if Hamon wins on Sunday, and significant Socialist support moves into Macron’s camp, that could change the dynamic.

Recent polls still show Fillon and Le Pen most likely to come first and second on April 23, going through to a decisive run-off vote on May 7 which Fillon would win.

However, some poll scenarios have put Macron in the second round in Fillon’s place, while others have him supplanting Le Pen. In those cases pollsters agree the 39 year-old former investment banker who has never held elected office would be hard to beat.