ROME (Reuters) - Former Italian Prime Minister Silvio Berlusconi signaled he was back in frontline politics on Wednesday, launching a broadside against the anti-system 5-Star Movement and predicting a surge in support for his party.

Slideshow ( 2 images )

Berlusconi, who had open heart surgery last year, cannot run for office due to a 2013 tax fraud conviction. But he remains head of his Forza Italia arty and hopes the European Court of Human Rights will soon rule that he can be a candidate.

After months keeping a relatively low-profile, the billionaire businessman has upped his media presence during campaigning for local elections in which second-round run-off ballots are set for Sunday with Berlusconi’s center-right bloc poised to make gains.

“Whether or not I can be a candidate, I am out on the campaign trail,” Berlusconi told one of Italy’s top talkshows on state television RAI. “I want to exceed the 20 percent threshold and think I can get past 30 percent.”

The latest EMG Acqua opinion poll published on Monday said Forza Italia was the third largest party in Italy on 14.1 percent, with 5-Star leading the pack on 28.4 percent and the ruling center-left Democratic Party on 26.8 percent.

The fourth-placed party, Berlusconi’s old ally the Northern League, was seen winning 13.8 percent. The League, which wants to drop the euro currency, has moved increasingly to the hard right in recent years, leading to tensions with Forza Italia.

Despite big differences on the national stage, the two parties have successfully joined forces for the municipal vote and are expected to chalk up gains on Sunday, including possibly ending 50 years of center-left rule in the port city of Genoa. [nL8N1J94AQ]

Berlusconi, 80, said he saw 5-Star, which was founded by comic Beppe Grillo, as the biggest danger facing Italy.

“I entered politics to combat the communist threat. Now there is another danger, that of Grillo and his supporters. The center-right has to remain united,” he said.

“Grillo’s bunch aren’t capable of anything ... 80 percent of them have never earned a penny,” he said.

Italy must hold national elections within a year, but does not yet have a coherent electoral system. With politicians squabbling over the issue, it looks increasingly likely that a proportional representation system will be adopted, making it highly unlikely that any group could govern alone. [nL8N1J61V1]

Berlusconi said that if the League joined forces with 5-Star, as some newspapers have speculated, he would leave Italy.

In an interview earlier in the day, he appeared to rule out any deal with the PD, which is headed by former Prime Minister Matteo Renzi. But on Wednesday night he indicated an accord might be possible, under the right circumstances.

“With me, the left would not be able to hike taxes,” he said, pointing to Germany, where coalition governments are the norm and rival parties are able to draw up joint programmes.