* Angry Sarkozy accuses Socialist rival of lying
* Duel seen as conservative leader's last hope of catching up
* Hollande leads runoff polls, Le Pen won't endorse Sarkozy
By Catherine Bremer and Paul Taylor
PARIS, May 3 (Reuters) - French President Nicolas Sarkozy and Socialist Francois Hollande clashed repeatedly in their only television debate but the conservative incumbent failed to land a knockout blow to shake his challenger's lead for Sunday's runoff.
Hollande, ahead in opinion polls by six to 10 points, seemed calm and unflappable during the nearly three-hour debate on Wednesday while Sarkozy, struggling to catch up with the moderate social democrat, was often agitated and tense.
Political commentators said the confrontation was no game-changer and probably only reinforced voters' opinions of their two champions in a contest that has been as much about style and personality as substance.
"This debate should not shift things and as Francois Hollande is in the position of favourite, he's the one that should benefit," said analyst Jerome Fourquet at pollster Ifop.
French television commentators concluded that Sarkozy had performed "like a boxer" and Hollande "like a judo fighter", using touches of wit and interjections to unbalance his adversary.
Hollande, 57, was confident and relaxed in early exchanges, saying he aimed to be "the president of justice", "the president of revival" and "the president of unity".
He said Sarkozy, also 57 and in office since 2007, had divided the French people for too long and was using the global economic crisis as an excuse for broken promises. "With you it's very simple: it's never your fault," Hollande said.
Sarkozy, fighting for his political life, repeatedly accused his opponent of lying about economic figures and reeled off reams of statistics in an attempt to unbalance his rival.
"Mr Hollande. When you lie so shamelessly, do I have to accept it?" he asked when his opponent said the president was always happy with his record.
The two sparred over Europe, which has become one of the biggest issues of the election race, along with the sickly economy, rife unemployment, nuclear power and immigration.
"The example I want to follow is Germany and not Spain or Greece," Sarkozy said, declaring that he and German Chancellor Angela Merkel had saved Greece from an economic wipeout and avoided the collapse of the euro currency.
"Europe has got over it," Sarkozy said of the crisis.
Hollande shot back: "Europe has not got over it. Europe is today facing a possible resurgence of the crisis with generalised austerity, and that's what I don't want."
Hollande, who vowed to push for a new focus on growth to allow the euro zone to convalesce, said people across Europe were watching the election in the hope it would change the bloc's economic direction for the better.
The conservative head of state and his centre-left rival have duelled at a distance for months, with Sarkozy accusing Hollande of being incompetent and a liar, and Hollande branding the incumbent a "failed president" and "a nasty piece of work".
Sarkozy, being punished for rife unemployment and a brash manner, is the most unpopular president to run for re-election. He was the first in recent history to lose a first-round vote, with Hollande benefitting from the anti-incumbent sentiment that has swept 11 euro zone leaders from office since 2009.
Wednesday's duel was carried live on channels that reach roughly half France's 44.5 million voters. The streets of Paris were unusually deserted with many people staying home to watch.
A handful of opinion polls due to land before Friday evening will measure any impact.
"It threw into sharper relief the strengths and weaknesses of both candidates: a tough-talking and often condescending Sarkozy determined to pick holes ... and a milder-mannered yet feisty Mr Hollande," said London analyst Nicholas Spiro. "There was no knock-out blow or major slip-up on either side."
Sarkozy suffered a setback on Tuesday when far-right leader Marine Le Pen - whose 17.9 percent score was the surprise of the first round - refused to endorse him. She vowed at a Paris rally to cast a blank vote and told her supporters to make their own choice, focusing most of her attacks on Sarkozy.
The issue of how to deal with the anti-immigration crusader and her supporters has tormented Sarkozy's UMP party all week, as a TNS Sofres opinion poll found a third of voters agreed with the National Front's positions.
The candidates tangled on immigration in the debate, with Sarkozy attacking Hollande's proposal to give long-term, non-European foreign residents the right to vote in local elections.
Sarkozy began campaigning weeks after the more plodding Hollande, vowing to boost industrial competitiveness, hold referendums on contentious policies, crack down on tax exiles and make the unemployed retrain as a condition for receiving benefits.
More recently, seeking to court the 6.4 million National Front voters, he has vowed to cut immigration and threatened to pull out of Europe's Schengen zone of passport-free travel unless the European Union's external borders are strengthened.
Recent polls show Hollande with a slightly tighter but still comfortable lead. A BVA survey on Wednesday put the gap 1 point narrower at 7 points, with the rivals at 53.5 and 46.5 percent. (1 = 0.7603 euros) (Additional reporting by Daniel Flynn, Alexandria Sage, John Irish, Pauline Mevel, Emmanuel Jarry and Elizabeth Pineau; Editing by Paul Taylor and Michael Roddy)