Socialist presidential frontrunner Francois Hollande urged his supporters to turn out en masse to vote in Sunday's first election round, warning that abstention helped the far-right eliminate the left from the same contest 10 years ago.

Hollande, tipped in opinion polls to win the two-round election by a comfortable margin, said he feared the positive predictions could lull Socialist voters into staying home, as in 2002.

Nothing is certain and nobody can tell what the final order and scores will be, the 57-year-old told BFM television three days from a ballot that will eliminate eight of the 10 contenders before a runoff on May 6.

Hollande and conservative incumbent Nicolas Sarkozy are expected to take the top two spots, with far-right leader Marine Le Pen, ranked third in many surveys, hoping to repeat the sensation her father Jean-Marie Le Pen achieved when he overtook Socialist Lionel Jospin to qualify for the runoff in 2002.

While Hollande looks set to become France's first left-wing president in 17 years, the vote will be driven more by anger at Sarkozy's style and his unfulfilled promises on job creation than enthusiasm for the Socialist candidate.

A survey by pollster LH2 published on Thursday gave Hollande 56 percent support for the May 6 runoff, against 44 percent for Sarkozy.

Sarkozy, who has sought as in 2007 to capture voters who may otherwise stray further right, also warned against voting for Le Pen, saying it would ultimately help his chief foe, Hollande.

A vote for Marine Le Pen serves Francois Hollande. If you want Socialist policy vote for the National Front, he said during a meeting in eastern Paris.

HAUNTING MEMORY

An abstention rate above 28 percent in the first round of the 2002 election and a large field of fringe candidates who split the mainstream vote turned the 2002 runoff into a standoff between Chirac and the extreme-right National Front candidate.

Some polls have suggested the turnout this year could fall further, to below 70 percent of France's 44.5 million voters.

Hollande said the memory of 2002 haunted him, and he noted that polls up to election day that year put Jospin in second place, four or five points ahead of Le Pen.

Three days later Le Pen pipped Jospin by a point, sending the anti-immigrant former paratrooper into the runoff, which conservative Jacques Chirac won with the help of votes from left-wingers who were urged to close ranks against Le Pen.

Marine Le Pen, who took over from her father as head of the National Front last year, trails further behind the two mainstream candidates in polls than her father did in 2002.

In the latest dozen polls, she scores between 14 and 17 percent of the first round vote, averaging 16, with Sarkozy taking 24 to 29 percent and Hollande 26 to 30 percent.

Sarkozy gained some ground in the polls after launching his campaign in mid-February and briefly overtook Hollande in surveys for the first round after an Islamist shooting drama in March put the focus on security.

However he has slipped back again in recent days, meaning a knockout punch in a TV debate before round two or an eleventh-hour alliance with a popular centrist may be his last hopes of securing a second term.

Greens Party candidate Eva Joly took Sarkozy-bashing to a new level on Wednesday, leading reporters on a tour of sites linked to bad publicity or sleaze allegations around the president.

Her tour included a swanky Champs Elysees nightspot where he feted his 2007 victory with millionaire friends, and the home of l'Oreal heiress Liliane Bettencourt, who is at the centre of an investigation into cash contributions to his 2007 campaign.

Sarkozy's camp called the stunt pitiful and the president kept up a defiant tone about his chances, telling Europe 1 radio: Let me remind you that there's never been a single election where the French people failed to spring a surprise.

(Additional reporting by Daniel Flynn and Elizabeth Pineau, Nick Vinocur and Yann Le Guernigou; editing by Geert De Clercq, Diana Abdallah and Paul Taylor)