By Maya Nikolaeva and John Irish
PARIS/CHATELLERAULT, France (Reuters) - Marine Le Pen's bid to defy the odds and win the French presidency risked a setback on Friday when her designated stand-in as National Front party leader stood down to defend himself against charges he shares the views of Holocaust deniers.
After an intense day of campaigning ahead of a May 7 run-off vote in which both the far-right's Le Pen and her centrist opponent Emmanuel Macron were carried back to the events of World War Two, surveys continued to show the independent Macron well ahead.
But in a couple of potential blows to the centrist favourite, defeated far-left leader Jean-Luc Melenchon stopped short of endorsing him, despite telling his faithful not to vote for Le Pen.
And another loser from the first round, Nicolas Dupont-Aignan, endorsed Le Pen, as expected.
The abrupt departure of Jean-Francois Jalkh from the National Front (FN) party leadership before he had even taken on the job raised ghosts of the FN's past and revived a furore sparked by Le Pen's father when he called the Nazi gas chambers a "detail" of history.
The renewed controversy threatens moves by Le Pen, who expelled her father, Jean-Marie Le Pen, from the party two years ago, to cleanse the FN's image of xenophobic and anti-semitic associations and make it more palatable to a broader electorate.
"There comes a time when the women and men of France must open their eyes to where the National Front comes from," Macron's campaign director Richard Ferrand said.
The presidential contest has blown apart traditional party loyalties, presenting voters with a stark choice between a resurgent far right, once a pariah in French politics, and a man whose political movement is less than a year old and who has never held elected office.
It sets Macron's enthusiasm for the European Union and call for pro-business reforms to boost growth against Le Pen's desire for France to close its borders to immigrants, unwind EU institutions and restrict imports to protect jobs.
Most opinion polls show him winning next Sunday, with 60 percent or more of the vote, a slightly smaller margin than a week ago.
Jalkh, a long-time ally of Le Pen senior who founded the National Front, was one of 35 FN members elected to parliament in the mid-1980s. He had been due to take over as interim party chief, a post Marine Le Pen has vacated to focus on the presidential race.
FN officials said Jalkh denies the allegations linking him to Holocaust deniers, and Le Pen herself later told BFM TV "there is no one in the leadership of the National Front who defends this sort of thesis".
At issue are comments attributed to Jalkh in a conversation with a researcher in 2005 about the work of a professor convicted more than once for questioning the scale of Jewish extermination in Nazi gas chambers during World War Two. Also unearthed was a 1991 report that said Jalkh attended a rally held by supporters of Marshal Philippe Petain, French wartime leader and Nazi collaborator, in July of that year.
Le Pen's father has been convicted of inciting racial hatred for his remarks on the Holocaust, and referred to them himself as recently as 2015.
GAY MARRIAGE JIBE
A thorn in her side, the 88 year-old has refused to be silent as his daughter bids for power.
He courted controversy again on Friday, saying a remembrance ceremony for a policeman killed last week by an attacker in Paris "exalted" the concept of gay marriage by giving the policeman's male partner the stage to speak in his memory.
Marine Le Pen attended the state ceremony with other political figures including Macron, and distanced herself from her father's comment on Friday.
"I felt it was a very dignified ceremony and I was very moved by the speech of his partner," she said.
As Le Pen and her party grappled with the latest turn of events, Macron had troubles too.
Melenchon, who came fourth in the election with about one on five votes of which about 40 percent are expected to back Macron, stopped short of endorsing him in a video released on YouTube.
Fringe right-wing candidate Dupont-Aignan, meanwhile, gave his backing to Le Pen as expected. He gathered 4.7 percent of the first round vote.
Macron on Friday campaigned at a village preserved as a monument to inhabitants killed by German SS soldiers in 1944.
"Deciding not to remember is to take the risk of repeating history," the 39-year-old said in Oradour-sur-Glane, near Limoges in central France, a thinly veiled attack on Le Pen for the anti-immigrant policies he says are fuelling divisions in French society.
Macron later gave a speech in Chatellerault, western France, taking his election battle to rural areas where disgruntled farmers have increasingly shied away from politicians or turned to the far-right following years of crisis.
(To view a graphic on 'French presidential election' click http://fingfx.thomsonreuters.com/gfx/rngs/FRANCE-ELECTION/010040SZ1RE/index.html)
(Additional reporting by Cyril Camu; Writing by Brian Love; Editing by Andrew Callus and Andrew Heavens)