PALERMO, Italy (Reuters) - Former Italian Prime Minister Silvio Berlusconi looked poised on Monday for a stunning political comeback as his rightist bloc claimed victory in an election in Sicily that puts it in pole position for a national vote due by next May. The regional Sicilian ballot, held on Sunday, was seen as a dry run for the nationwide election, with many of the island s problems reflecting those of the country as a whole - high unemployment, a debt mountain and sluggish economic growth. An influx of migrants, many of whom arrive in Sicily after being rescued in the Mediterranean, was also a key issue. With all of the votes counted, a center-right bloc backed by the four-times prime minister was more than 5 percentage points ahead of the anti-establishment 5-Star Movement, with the center left, which governs at the national level, a distant third.  Sicily, just as I asked, has chosen the path of real, serious, constructive change, based on honesty, competence and experience,  the 81-year-old said in a video posted on Facebook. Nello Musumeci, the center right s candidate for governor of the island, had 39.8 percent of the vote, while the 5-Star s Giancarlo Cancelleri had 34.7 percent. The center left s Fabrizio Micari was lagging on 18.7 percent. The result puts Berlusconi back on the political map after years of sex scandals and graft allegations which had seemed to have reduced the billionaire media mogul to a spent force. Berlusconi cannot run for office due to a 2013 tax fraud conviction. But he hopes the European Court of Human Rights overturns this ban when it reviews his case later this year,  which would pave the way for a possible national challenge. He returned to the fray after open-heart surgery last year and campaigned actively in Sicily. Even if the courts deny him the chance to run, he would be an influential figure should the center right capture power again nationally. The result on the island deals a stinging blow to another former prime minister, Matteo Renzi, head of the ruling Democratic Party (PD), which is locked in feuding with erstwhile leftist partners. After a raft of vote setbacks in recent years, Renzi has many critics inside the PD who may now try to mount a challenge to his leadership.  Defiant in its defeat, the anti-system 5-Star Movement vowed to reach national government next year, and its leader Luigi Di Maio declared the PD  politically dead . Opinion polls suggest the center right will win next year s national vote, but a recent change to the electoral law is likely to stop any one bloc winning an absolute majority of seats, resulting in political gridlock. Sicily is traditionally a center-right stronghold which was poached by the PD in 2012 thanks to splits in the conservative bloc. This time, Berlusconi reunited the coalition behind a widely respected leader with a far-right background. Berlusconi s allies, the Brothers of Italy and the Northern League, reaped rewards with anti-immigrant campaigns, suggesting this will remain high on the agenda for the national vote.  From Sicily we will demonstrate that this is a winning model that can triumph at a national level,  said Giorgia Meloni, the leader of the right-wing Brothers of Italy party which is the junior partner in the center-right alliance. The centre-left government has moved this year to shut down the flow of migrants from Libya after more than 600,000, mainly Africans, reached Italy over the past four years. But the issue has dented support for the center left, which has further damaged itself by falling prey to ferocious schisms. The maverick 5-Star, founded by comedian Beppe Grillo, had campaigned relentlessly for months in Sicily, looking to take charge of its first region after a string of successes in municipal ballots in recent years, including in Rome and Turin. Di Maio said the party had been penalized in Sicily by low turnout - a record of fewer than half of those eligible cast a vote, showing flagging interest in politics in Italy following years of economic downturn.  In two or three months I think many of those who abstained will regret not going to vote,  Di Maio said, insisting that if turnout had been 3 or 4 points higher it could have tilted the result in the movement s favor. Despite losing to the center right, the 5-Star Movement s result was a leap from 2012, when its candidate won only 18 percent of the vote in the regional polls.   Investors are worried 5-Star might win control of the country. The party bases its appeal mainly on a campaign against corruption and vested interests in Italy, but it has pulled back from a pledge to hold a referendum on continued membership of the euro. Markets were little changed on Monday. 