By Catherine Bremer and Brian Love
PARIS (Reuters) - A strong showing by hardline leftist Arnaud Montebourg in France's Socialist Party primary vote makes the selection of a moderate candidate less of a certainty and could drag the party's 2012 presidential campaign further to the left.
Francois Hollande, a moderate who wants to curb the public deficit and foster closer European integration, won 39 percent in Sunday's first-round vote, beating Martine Aubry, a more old-school leftist who secured 31 percent, according to results released Monday with 86.5 percent of the vote counted.
Hollande has long been the favorite to challenge President Nicolas Sarkozy next April. But an unexpectedly high 17 percent score by Montebourg -- who wants to row back on globalization and have the state take partial control of banks -- raises the possibility that Aubry could win the October 16 runoff instead.
It also suggests that Hollande may have to lean further leftwards to nail down the candidacy and, if he wins that, to gather critical voting mass for 2012.
Analysts say the second round of the primary is now much harder to call, making it in both candidates' interests to cozy up to the newly influential Montebourg in the days ahead.
"Things are basically very open. It's more complicated than it was before," said Francois Miquet-Marty of pollster Viavoice.
"Montebourg is closer ideologically to Aubry but the personalities will count too. This period between the two rounds is crucial. It's all about the balance between credibility and a left-wing identity. Hollande is going to have to show that he belongs to the left," he said.
Opinion polls show that both Hollande and Aubry, bitter rivals and former party leaders, could unseat the conservative Sarkozy if the election, scheduled for April, were held today.
Investors have been relatively unfazed to date by the left's lead in election polls. But the prospect of an Aubry candidacy or of Hollande tilting further left could rattle some foreign observers, already fretting over France's shaky public finances and its rescue, with Belgium, of Dexia bank.
Montebourg's outspoken stance against globalization and bank sector profligacy during Socialist TV debates raises the specter of some of his more radical ideas, such as putting government officials with veto power on the boards of banks, having to be embraced by whoever the left's candidate is.
"How can those who advocate deglobalisation, a Sixth Republic, a radical left, vote for somebody who is the furthest away from these political theories?" said Jean-Christophe Cambadelis, a prominent Socialist and backer of Aubry.
Hollande conceded he may have to take Montebourg's ideas into account. "A message has been voiced ... through Arnaud Montebourg, a will for protection from globalization and for more morals in political life. I hear it," he told RTL radio.
The left-leaning daily Liberation saw Montebourg having a clear influence on the left's campaign. "The very big score of (Montebourg), who defended deglobalisation and a line that is left of left, gives him a real influence on the ideological and political profile of the victor," it said in an editorial.
LEFT HAS WIND IN SAILS
The left is bent on ousting the conservatives from the presidential palace after three terms in opposition. Polls show most French want a change of government, due largely to frustration with Sarkozy's economic management and the perception he has done little for jobs or spending power.
Polls have pegged Hollande, a witty if unexciting party veteran who has never been a government minister, as favorite for the left ever since the downfall of the party's erstwhile star, Dominique Strauss-Kahn, in a sex scandal this year.
The Socialists' victory in Senate elections last month, ending conservative control of what had been a bastion of the right for half a century, triggered muttering that Sarkozy may be the wrong person to stand for the ruling UMP party.
Many of those voters who supported Sarkozy for his down-to-earth manner and message of change in 2007 now resent a manner that critics say is impulsive and brash, as well as a view that he has favored the wealthy with tax breaks.
Focused this week on finding ways to counter a sovereign debt crisis that threatens a global recession, Sarkozy is not expected to confirm he will run for a second term until after France's G20 summit in early November.
Voting in the Socialist primary was open to anyone professing leftist views and was not restricted to party members, giving a view of how the wider public might vote.
Final results of Sunday's vote by more than 2.5 million people were delayed but should be in line with current figures, Socialist Party head Harlem Desir told a news conference.
Even if Montebourg does not explicitly call on his backers to vote for Aubry, the daughter of former European Commission president Jacques Delors and known for her role in introducing the 35-hour work week, many are expected to opt for her.
Supporters of Segolene Royal, who wept after winning just 7 percent of Sunday's vote four years over she lost the 2007 election to Sarkozy, may also plump for Aubry over Hollande, Royal's estranged former partner and father of her children.
Montebourg met Royal Monday, but his spokesman said that did not mean the pair would necessarily jointly back Aubry or Hollande, who will face off in a TV debate Wednesday.
"Given his big score yesterday, it's likely he will be at the center of a great deal of attention," Aubry supporter and ex-UNEF student union head Bruno Juillard said of Montebourg.
(Writing by Catherine Bremer; Editing by Mark Heinrich)