(Reuters) - The influential speaker of Italy's lower house refused to step down on Friday after being censured by his own party, and said his supporters could vote against the government of former ally Prime Minister Silvio Berlusconi.

"Obviously I have no intention of resigning," Gianfranco Fini told a news conference a day after Berlusconi effectively booted him out of the party they founded jointly two years ago, raising the specter of early elections.

A combative Fini attacked Berlusconi for "having not exactly a liberal concept of democracy" and for trying to run a government like an autocratic CEO, "which has nothing to do with our democratic institutions."

Standing behind the 58-year-old Fini were parliamentarians who will join him in his party rebellion, calling the faction Freedom and Future for Italy.

A parliamentary official later said they had 33 members in the lower house plus Fini, enabling them to deprive Berlusconi of a majority there. They have 10 supporters in the Senate, which could cut Berlusconi's majority there to just two votes.

Berlusconi, who accused Fini of being a traitor and conspirator and trying to inflict a "slow death" to their party, met party leaders late on Friday to decide his next move.

Fini said his fellow rebels would "loyally support the government every time it acts within the framework of the electoral program, but will not hesitate to fight proposals that are unfair or damaging to the wider interest."

He did not mention the risk of early elections, which commentators said were now a real possibility.

After months of tension and even open hostility between the estranged conservatives, Berlusconi's party issued a tough document censuring Fini, saying his actions and comments no longer reflected the ideals of the party he helped found.

The coalition, made up of the People of Freedom (PDL) and the Northern League, needs a majority of 316 in the lower house. Before the split, it could count on up to 344 votes, including 14 from smaller parties who decide votes on an ad hoc basis.

But the new numbers could deprive Berlusconi of this comfortable cushion of nearly 30 votes, leaving him prey to whims of tiny parties or even demands from the Northern League, which caused the collapse of his first government in 1994.

EARLY ELECTIONS

The situation caused by the de facto implosion of the center-right was unprecedented, with no institutional guidelines on the sequence of steps over the next few days or weeks.

Several commentators said on Friday Berlusconi had told his aides that if there were enough defectors, he would prefer early polls as he is convinced his party will do well without Fini.

Fini has enraged the prime minister by hammering away at the theme of morality and legality in government, and insisting that officials implicated in judicial investigations should resign.

Commentators said if the political situation becomes untenable, President Giorgio Napolitano could appoint an interim government to run business until new elections, like an administration headed by former Finance Minister Lamberto Dini in 1995 after the collapse of Berlusconi's first government.

Napolitano, a former communist who has often clashed with Berlusconi, discussed the crisis with opposition leaders, who said they wanted Berlusconi to resign.

Berlusconi has been locked for months in conflict with Fini, who was once considered his heir as leader of the center-right.

The censure document, which was signed by all but three of the 36 members of the presidency of the PDL, rebuked Fini for positions it said were incompatible with the party line.

It accused Fini, who co-founded the PDL with Berlusconi two years ago, of waging "political opposition" within his own party and of trying to administer a "slow death" to it.

At his news conference, Fini listed the charges against him like a defendant in the dock and defiantly rejected each one.

Fini, an ex neo-Fascist, dissolved his own National Alliance party to merge it with Berlusconi's Forza Italia after nearly 14 years of supporting him in three previous governments.

(Writing by Philip Pullella; additional reporting by Roberto Landucci, James Mackenzie and Silvia Aloisi; Editing by Maria Golovnina)