* Adversaries may have to unite if Italy is to be governable
* Former communist credited with pragmatism
* Vendola and Monti may be forced into coalition
By Steve Scherer and Naomi O'Leary
ROME, Feb 21 (Reuters) - Italy's chance of stable government after elections this weekend may rely on forcing two awkward partners into coalition: former European Commissioner Mario Monti and an openly gay leftist he has vowed not to work with.
The mutual sniping between Monti and Nichi Vendola, governor of the southern region of Puglia, has intensified during the final weeks of campaigning for elections on Sunday and Monday and both have declared their visions for Italy "incompatible".
Yet polls indicate the centre-left coalition, in which Vendola's Left Ecology Freedom (SEL) is the main partner allied to the larger Democratic Party (PD), may have to join forces with Monti's centrist group in order to rule.
Monti has called Vendola, whose defence of welfare and labour rights appeal to traditional left-wingers, an obstacle to much needed economic reforms and urged PD leader Pier Luigi Bersani, most likely head of the next government, to drop him.
With his bowl of silver hair and a sleepy expression, the 54-year-old Vendola, has been equally critical of Monti, who headed a government of technocrats to haul Italy back from economic collapse after Silvio Berlusconi quit power in 2011.
"Monti's year in government left the country wounded," Vendola told foreign reporters in Rome on Thursday. "Austerity must be loosened to restore necessary oxygen to an economy that is out of breath."
Sporting a diamond-studded hoop earring, Vendola said Monti was "not the same" as centre-right leader Silvio Berlusconi but his social agenda was "unsuitable for younger generations".
Monti, a devout Catholic, said last month he was against gay marriage. Vendola, also a practising Catholic, has long campaigned for the right of same-sex couples to wed, so he can marry his boyfriend.
In Italy's socially conservative south, Vendola shocked even his own party by winning the governorship of Puglia - the heel of the Italian boot - in 2005. He was re-elected five years later with a larger share of the vote.
Vendola proudly describes himself as coming from a "Catholic and communist" southern family, and joined his first communist organisation at 14.
Critics suggest if Vendola agrees to govern with Monti, he could hinder the radical reforms that economists say are necessary to revive Italy's stagnant economy.
Worse, they fear he could follow the footsteps of his mentor, former communist leader Fausto Bertinotti, who brought down the centre-left government in 1998.
Some say that is less likely to happen under Vendola as his carefully cultivated image as an idealist - a sometime poet whose florid speaking style is edged with a lisp - belies a steely pragmatism.
A senior official at the Bank of Italy said Vendola governed Puglia for eight years more "like a Christian Democrat" than a communist, and the business community has generally praised his stewardship.
"As governor, I saw in him a pragmatism that, frankly, I did not expect at all," Domenico Di Paola, the chief manager of Puglia's airports, which are controlled by the regional government, told Reuters.
"Before the vote Monti and Vendola have to be enemies," said Innocenzo Cipolletta, former chief economist for Italy's biggest business lobby and president of the University of Trento.
"Afterwards, since they are both reasonable people who care about the good of the country, they will find a way to reach an understanding."
Bersani, who signed a joint political programme with Vendola last year, says he will not drop his coalition partner and will mediate between Vendola and Monti if an alliance is needed.
"It's useless for people to tell me they won't deal with Vendola, because for me that is the same as saying they won't deal with me," Bersani said at a rally in Vendola's home region.
Vendola and Monti may have little choice but to get along. An inconclusive result could mean the only alternative to joining forces would be to hold fresh elections.
"Vendola is no fool, and Monti cannot take responsibility for making the country ungovernable," said Maurizio Pessato, vice chairman of polling institute SWG.
"They both know if they screw up they will all end up sitting on their couches at home instead of in parliament."