* Bersani says economy, jobs will be top priority if elected
* Says Italians need "truth not fairy tales" about crisis
* Commentators says Bersani now has to re-unify party
By Philip Pullella
ROME, Dec 2 (Reuters) - Pier Luigi Bersani won a run-off primary election by a huge margin on Sunday to become the Italian centre-left candidate for prime minister in national elections early next year.
In his victory speech, Bersani promised to tackle Italy's economic crisis and high unemployment if elected and said his Democratic Party would have to win by telling Italians "the truth, not fairy tales" about the grave situation.
Bersani has said repeatedly that in power he would stick to tough budget commitments made by technocrat Prime Minister Mario Monti, but seek to soften the impact on workers and the poor and put more emphasis on economic growth.
Markets have expressed some wariness over an alliance between Bersani, who is head of the centre-left Democratic Party and a former communist, and a party called Left, Ecology and Freedom.
With more than 80 percent of the 9,200 polling places reporting, Bersani had 60.9 percent of votes to 39.1 percent for Renzi. The results were in line with two exit polls.
"I was always confident and tranquil but I did not expect to win by this much," Bersani told a victory rally after his rival, Florence mayor and fellow Democratic Party member Matteo Renzi, conceded defeat.
Bersani, 61, will now stand in national elections, likely in March, against a still-to-be-chosen centre-right candidate to take over from Monti.
"It won't be simple but we can't ignore the fact that we are facing the greatest crisis of the post-war period and the greatest problem of all is jobs," he said of Italy's economic situation.
Italy's unemployment stood at 11.1 percent in October and its public debt is equivalent to 126 percent of national output.
During the campaign, the contrast was marked between the bald, slow speaking professorial Bersani and Renzi, who bounced around platforms at rallies in open shirts and jeans.
Renzi had painted himself as a Kennedy-esque reformer, saying Italy's largest centre-left party needed a big shake-up.
He had accused the older generation of the Democratic Party of failing to present a credible alternative, allowing former Prime Minister Silvio Berlusconi's centre right to govern for so long.
Despite the big victory, commentators said Bersani would now have to woo back some 40 percent of the party, many of them young, who voted for Renzi.
Monti, favourite of the business community, has said he will not be a candidate next year but might come back if the election does not provide a clear winner.
Another possible future role for him is as president of the republic and guarantor that austerity reforms agreed with Italy's European partners continue.
Berlusconi's scandal-plagued right, forced from government by the financial crisis a year ago, is in disarray.
Berlusconi said on Monday he would wait to see who wins the centre-left primary before deciding whether to run himself. He has repeatedly changed his mind in the last few weeks on whether to do so.
Some analysts said the victory by Bersani might spur Berlusconi to get back into the game.
"Indeed, a Bersani-led PD is likely to embolden Silvio Berlusconi to form his own party in the hope of keeping the centre left out of power and reviving the fortunes of Italy's centre right," said Nicholas Spiro, managing director of Spiro Sovereign Strategy in London.
The centre-right is divided over whether they should hold its own primary. Fabrizio Cicchitto, head of Berlusconi's PDL party in the lower house, who wanted primaries said: "We have paid and will continue to pay for this political void".