PARIS (Reuters) - Defeated Socialist Party presidential hopeful Segolene Royal will back party favorite Francois Hollande, her former companion, in a primary runoff on Sunday, giving him a small boost against rival Martine Aubry.
Royal, who wept after coming fourth in Sunday's first-round primary vote with 7 percent to Hollande's 39 percent, said in a statement she would back the man who is father of her four children because he was best placed to win.
"We must give impetus to the candidate with a clear lead that will not leave the right any foothold," Royal said.
Her move came as a second poll showed Hollande, a moderate left-winger, remains in the lead by several points to be picked as the Socialist candidate for the 2012 presidential election.
Hollande's victory over Aubry, a stauncher leftist who helped bring in France's 35-hour work week, looks less certain since hardline leftist Arnaud Montebourg landed in third place in the first round with a stronger than expected 17 percent, suggesting strong support for his more radical ideas.
In the first poll of second-round voting plans since then, an Opinionway survey of left-wing voters on Tuesday showed Hollande's predicted score slipped four points to 54 percent while Aubry's rose four points to 46 percent.
A second survey on Wednesday by Harris Interactive found 53 percent of left-wing voters would back Hollande in the second round of the Socialist primary on Sunday against 47 percent for his rival Martine Aubry, a more old-school leftist.
Hollande and Royal separated in 2007, shortly after Royal lost that year's presidential election to conservative Nicolas Sarkozy, following a 29-year relationship that made them the golden couple of the French left.
Montebourg, whose support could be a deciding factor in Sunday's primary runoff, has said he is waiting until after a final TV debate between Hollande and Aubry on Wednesday evening before deciding which candidate to back.
(Reporting by Brian Love; Writing by Catherine Bremer Editing by Maria Golovnina)