Comedian's Sicily success signals huge shift in Italian politics

* Grillo's 5-Star Movement a growing menace to establishment

* Economic crisis and corruption driving shift

* Vote for Berlusconi's party collapses in Sicily

By Steve Scherer

ROME, Oct 30 (Reuters) - The emergence of the anti-establishment 5-Star Movement as the largest party in Sicilian elections signals a radical shift in Italy's political landscape, with parliamentary elections five months away.

Voters in the regional polls dramatically abandoned the centre-right party of former prime minister Silvio Berlusconi, 76, convicted of tax fraud last week and still facing charges of having sex with an underaged prostitute.

Dominant both in Sicily and in Italy for more than a decade, it now risks being swept away by economic crisis and a tide of disgust with political corruption and patronage that also threatens the established parties of the centre and left.

The euro zone's third-largest economy fell into recession in the middle of last year and has yet to emerge.

Prime Minister Mario Monti, called in to replace the discredited Berlusconi, has imposed new taxes to curb the budget deficit and rein in borrowing, further hurting households.

Italy's regional governments, including Sicily's, became the focus of popular outrage after Italian investigators uncovered widespread waste and graft by ruling parties, despite severe cuts imposed to combat the financial crisis.

Giancarlo Cancelleri, a 37-year-old surveyor who has never held office, took 18 percent for comic Beppe Grillo's 5-Star Movement in Sicily, campaigning against Monti's austerity and the island's chronic corruption.

Berlusconi slammed Monti's policies and threatened to pull support for his government a day before the Sicily vote, a move disowned by senior members of his own People of Liberty (PDL) party, including his possible successor, Angelino Alfano.

"As far as we are concerned, the Monti government will continue," Alfano, the PDL's secretary, said on Monday after the votes were counted.

The PDL has said it will support Monti's government in a confidence vote to be held later on Tuesday, called to pass an anti-corruption law in parliament.

"I have no reason to believe that the collaborative and positive things we have done so far cannot be continued in coming months," Economy Minister Vittorio Grilli said.

President Giorgio Napolitano, who has the power to dissolve parliament and was the architect of the Monti government, urged political groups to continue the legislature until its natural end in spring.

EMPTY THREAT

Berlusconi's threat to topple Monti may be empty, but the 5-Star Movement is a real menace to the parties supporting Monti's right-left government.

The Movement emerged as the biggest single party in Sicily, while Berlusconi's party, which won 46 percent of the island's vote in the 2008 national ballot, got less than 13 percent.

"The 5-Star Movement could become the biggest party in Italy," Roberto Weber, chairman of SWG polling institute, said on Tuesday. "On a national scale, our latest polls show it pulling more than 22 percent at a national level."

The Democratic Party (PD) also perceives Grillo's movement as its greatest threat, a senior party source said on Tuesday, although the PD together with the Union of the Centre (UDC) won the Sicilian vote overall.

The 5-Star Movement's Cancelleri ruled out supporting the winners in the local legislature, saying the movement's representatives were like "bitter spinsters who never have boyfriends".

Instead, Cancelleri said, the bloc would evaluate each of the government's proposals individually.

Grillo, who has ruled out standing for parliament himself, says his movement would play a similar role in the national parliament. It will not compromise in order to join a government and will be an active opposition unless it can win on its own.

"Sicily is always a bellwether for national political choices and in this case the vote told us that the only response to anti-politics is an alliance between progressives and moderates," UDC leader Pier Ferdinando Casini said after the Sicilian vote.

The PD and the UDC are not allies in next year's national vote, though they are considered possible partners after the election.

Two separate polls published on Tuesday underscored the 5-Star Movement's growing popularity, to the detriment of the PDL and PD.

Pollster SWG said 40 percent of 5-Star Movement voters in Sicily came from the centre left and 25 percent from the centre right. A poll by Ispo said 60 percent of voters nationally either planned to abstain or vote for Grillo's bloc.

"Many Sicilians, and as research shows, many Italians, do not have faith any more in the proposals of the traditional parties and in their ability to resolve the problems of their island or their nation," Ispo head Renato Mannheimer wrote.

In the 1994 elections, corruption scandals led to the demise of the once-preeminent Christian Democrats. As they and the Socialists exited the political stage, Berlusconi formed a party that took their place.

In 2012, increasingly the question seems to be: Who will replace Berlusconi?