By Catherine Bremer
PARIS (Reuters) - President Nicolas Sarkozy may top the first round of a presidential election this month but still lose a runoff on May 6 as most fringe voters say they will back Socialist challenger Francois Hollande, opinion polls show.
Sarkozy pulled into the lead for the April 22 first ballot in yet another poll on Tuesday, but surveys for the second round have stabilized with Hollande firmly ahead, as supporters of other candidates prefer him to the conservative incumbent.
Hampered by a widespread dislike of his personal style and anger over economic gloom, Sarkozy has clawed back some ground with a high-impact campaign and his handling of a shooting drama in March - but his chances of escaping defeat look slim.
The second-round momentum has shifted against Sarkozy as hard leftist Jean-Luc Melenchon has surged in recent weeks, stealing protest votes from far-right leader Marine Le Pen, who has seen her support ebb.
Sarkozy is banking on strong second-round support from Le Pen supporters, whom he has wooed with a tough line on immigration, but two polls on Tuesday showed only 46-49 percent of Le Pen voters plan to switch to Sarkozy in round two, with others undecided, abstaining or voting Hollande.
While one voter in five is still undecided for the runoff, a study by the left-leaning Fondation Jean Jaures think-tank shows that of those who have decided, only 1.3 percent expect to change their minds, versus 9 percent who might change their minds for round one.
"Our morale is good but we will devote these final weeks to battling hard," Hollande's campaign manager Pierre Moscovici told a briefing for foreign media, saying the party's chief worry was a low turnout.
A survey by pollster Ifop at the weekend found 32 percent of respondents planned to abstain, higher than the 28.4 percent abstention rate in the 2002 election when low turnout helped then National Front leader Jean-Marie Le Pen knock Socialist Prime Minister Lionel Jospin out to reach the runoff.
SARKOZY IN CORNER
Sarkozy is set to unveil his manifesto at a news conference on Thursday, 16 days from the first round of voting and more than two months after Hollande presented his 60-point program.
While Hollande has lost steam, making few headlines since proposing a 75 percent "millionaires tax" at the end of February, Melenchon has stolen the spotlight with combative oratory that appeals to the urban middle-class as much as to disgruntled blue-collar workers.
An Ifop poll published in the daily Le Monde was the latest survey to show Sarkozy pulling into the lead for round one, scoring 29.5 percent to Hollande's 27.5 percent, with Melenchon overtaking Le Pen to stand in third place.
Le Pen has lost ground partly due to her economic program, which includes taking France out of the euro.
The poll found 81 percent of Melenchon voters and 40 percent of centrist Francois Bayrou's backers would switch to Hollande in round two, giving him 55 percent to Sarkozy's 45 percent.
Some 16 percent of Le Pen backers would vote Hollande in the runoff, the poll found, while Sarkozy would only get 3 percent of Melenchon voters, 32 percent of Bayrou supporters and 49 percent of Le Pen voters.
A BVA poll for Le Parisien daily showed similar results, summed it up in a cartoon showing an advisor telling Sarkozy, "First the good news: you'll make it to the second round."
One of the least popular French presidents in recent history, Sarkozy opted to delay his manifesto and unveil proposals one-by-one for maximum impact.
He has vowed to hold policy referendums, to cut immigration, to make the long-term unemployed undergo training to get benefits, to quit the European Union's open-border scheme unless frontiers are reinforced and to push for a Buy European Act.
Hollande is running on a tax-and-spend platform that would raise taxes on the rich and on companies to fund investments in education and state-aided jobs.
A separate survey by pollster Harris gave Sarkozy a three-point lead over Hollande in round one, 29 percent to 26 percent, but found Hollande would still win the runoff by 53 percent to Sarkozy's 47 percent.