Ségolène Royal puts split behind her as she backs ex-partner for presidency

Beaten candidate puts aside rancour to support Hollande's bid to win presidential nomination

It might be described as a Royal pardon. The former French presidential candidate, Ségolène Royal, yesterday put aside personal bitterness and endorsed her former partner, François Hollande, in the second round of the Socialist presidential primary.

Her decision took French political commentators by surprise. Ms Royal, 58, the failed Socialist contender in 2007, wept in public last Sunday when she took only 6.9 per cent of the vote in the first round of the primary election to choose a centre-left candidate for the election next spring.

Ms Royal was expected to refuse to endorse the remaining candidates, Mr Hollande, 57, and the Socialist party leader, Martine Aubry, 60. She has personal grievances with both.

She was in a relationship with Mr Hollande for 29 years before their relationship ended acrimoniously just after the 2007 presidential campaign. They have four children together.

Ms Royal is also known to dislike and distrust Ms Aubry, who narrowly defeated her for the leadership of the Parti Socialiste in 2008. At the time there were accusations of cheating on both sides and Ms Aubry has made no secret of her contempt for Ms Royal.

Despite being expected to withhold backing from both remaining candidates, Ms Royal announced that she was supporting her former partner because he was best placed to win by a convincing margin in this Sunday's run-off and go on to defeat President Nicolas Sarkozy in the presidential election next year.

"France faces a decisive moment in its history," she said.

"We on the Left don't have the right to mess up this appointment with the people of France, who expect us to be united in their service." Mr Hollande described his former partner's decision as "elegant and responsible".

He said that she, more than anyone, knew the importance of party unity – a reference to the in-fighting and personal hatreds that weakened her campaign in 2007.

In the first round of the primary, Mr Hollande topped the poll with 39.2 per cent and Ms Aubry came second with 30.4 per cent.

A poll by Opinionway on Tuesday suggested that Mr Hollande would win on Sunday by 54 to 46 per cent.

More than 60 per cent of Ms Royal's supporters told pollsters that they would switch their vote to Ms Aubry.

It remains to be seen whether her endorsement will change their minds.

The outcome of the primary will also depend partly on the 17 per cent who voted for Arnaud Montebourg, the most left-wing candidate.