PARIS - Former French prime minister Alain Juppe ruled himself out on Monday as an alternative to his right-wing party colleague Francois Fillon whose campaign has been thrown into chaos by a fake job scandal.

Juppe, 71, was the most likely candidate to step in for Fillon and try to unite their deeply divided Republicans party only seven weeks from the start of the two-stage election.

Polls suggest Juppe would be more popular with voters, but the centrist is considered too soft on immigration and other social issues for many of Fillon's supporters and the right flank of the party.

"I confirm for a final time that I will not be a candidate to be president of the republic," Juppe said in a downbeat statement that criticized Fillon and the "confused" conditions for the election.

His decision removes a major rival for Fillon, whose bid for the presidency remains on track despite mounting criticism within the party and falling poll numbers.

The conservative 63-year-old was once a clear favorite to be France's next leader but his campaign is mired in accusations he used public funds to pay his wife hundreds of thousands of dollars for fake parliamentary jobs.

"No one today can prevent me being a candidate," he said on Sunday, adding that the accusations against him were "aimed at stopping me being a candidate".

The chaos in Fillon's camp has made an already unpredictable election even harder to call.

It appears to have benefited centrist pro-business candidate Emmanuel Macron in particular, as well as far-right leader Marine Le Pen, who are shown by polls as the top two candidates in the first round on April 23.

Poll favors Macron

Polls suggested that Macron, 39, would beat Le Pen in the decisive second round, but after the shock of Donald Trump's rise in the United States and Britain's vote to leave the European Union, analysts caution against bold predictions.

Former president Nicolas Sarkozy piled pressure on Fillon to meet Juppe and find a way out of the crisis.

Sarkozy, who picked Fillon as his prime minister from 2007-12, urged Fillon and Juppe to meet "to find a dignified and credible way out of this situation which cannot continue and which is creating serious problems for the French people".

A number of Sarkozy's closest allies have called on Fillon to step aside.

The current French leader, Francois Hollande, also warned in an interview with six European papers published on Monday that the threat of a Le Pen presidency was real but that he would fight to prevent it happening.

"The far right has not been so high (in the polls) for more than 30 years but France will not give in," the president said.