An influential French centrist politician struck an alliance with presidential candidate Emmanuel Macron on Wednesday that is likely to boost the independent's chances in the tightly contested election.
The announcement by Francois Bayrou, 65, a former education minister who has run for president three times and polled 9 percent of the vote when he stood in 2012, could tip the odds in favour of Macron getting into a runoff against far-right leader Marine Le Pen.
"We are in an extremely risky situation, and to tackle this exceptional situation, I think we need an exceptional response," said Bayrou, referring to a campaign that has been marked by scandals and upsets in which several big names have disappeared.
"I have decided to offer Emmanuel Macron an alliance. The danger is too big, we must change things," he told a news conference, describing his decision not to run for president himself as a "sacrifice".
In a statement to Reuters, Macron said he accepted Bayrou's offer, which he labelled a "turning point in the campaign".
Macron, a 39-year-old ex-banker and comparative political novice who has never held elected office, says he seeks to transcend the classic left-right divide in French politics. He has drawn huge crowds to rallies that easily equal those of his closest rivals.
The election is held in two stages on April 23 with a runoff vote between the top two candidates on May 7.
Opinion polls put Macron neck-and-neck with conservative Francois Fillon, a former prime minister, to get into the runoff against Le Pen, head of the anti-immigrant and anti-European Union National Front.
Fillon, 62, was once the frontrunner to win election but his campaign has been hit hard by a scandal over salaries paid to his wife and children out of public funds for work they may not have carried out. He says they did carry out the work for which they were paid.
Surveys say either Macron or Fillon would then go on to beat Le Pen in the knockout run-off vote.
Elabe pollster head Bernard Sananes said that although Bayrou's decision not to run did not radically change the polling arithmetic, it gave the Macron's campaign a boost after it had lost some momentum recently.
"The dynamic in an election campaign is always bigger than the maths (of polls). Will it add up? - Probably, because the electorate of Francois Bayrou and Emmanuel Macron are ultimately pretty close," Sananes said.
Bayrou's announcement pushed the euro up against the dollar and French bond yields, which had risen because of fears of rising support for Le Pen, fell about 5 basis points.
Bayrou said he would hold talks with Macron in the coming hours and set several conditions for supporting him, although Macron's camp are unlikely to find them tough to swallow.
They include passing a law against conflicts of interest and introducing proportional voting in the lower house of parliament. Macron has said in the past he wanted more proportional voting and less corruption in the echelons of power.
In a further twist in an election campaign marked by scandals and upsets, Le Pen's chief of staff was put under formal investigation in a probe into the alleged misuse of European Union funds to pay parliamentary assistants, Le Pen's lawyer said.
Le Pen has denied any wrongdoing.
Earlier police detained her chief of staff Catherine Griset and her bodyguard Thierry Legier for questioning. Legier was later released without being put under formal investigation.
Both are key figures in the probe which followed demands by the European Parliament that Le Pen repay money she is accused of wrongly paying the two.
Wary that her image and lead position in opinion polls might equally be hurt, Le Pen said she was convinced voters would not fall for moves designed to derail her and her campaign.
Drawing a distinction between the probe against her and the fraud investigation against Fillon, she said: "The French can tell the difference between genuine scandals and political dirty-tricks."
Bayrou himself had little chance of reaching the runoff between the top two contenders, given the 5-6 percent that pollsters saw him as likely to get in the first round.
Describing French democracy as under threat, he said that the conservatives under Fillon were riddled with scandals and the Socialists, whom he backed in 2012, were in disarray, a situation that could pave the way for the far-right.
"What's at stake with this alliance is to restore hope," Bayrou said.
Polls see little chance of the Socialists recovering enough to contest the election robustly after five years of unpopular rule by President Francois Hollande.