By Isla Binnie
ROME (Reuters) - Italy's 5-Star Movement told roaring supporters it was close to winning a looming election at the end of campaigning on Friday as its main rivals worried about the anti-establishment party's popularity.
Pollsters predict Sunday's parliamentary election will result in a hung parliament in which former prime minister Silvio Berlusconi's alliance of center-right groups will be the largest bloc and 5-Star the biggest single party.
The ruling center-left Democratic Party (PD) has failed to capitalize on a tentative economic recovery following the worst recession since World War Two, and the coalition it heads could end up in third place.
"We are a step away from victory," 5-Star leader Luigi Di Maio said at a rally in Rome's Piazza del Popolo, where a crowd waved flags and chanted "honesty", the group's buzzword.
A blackout on opinion polls was imposed two weeks ago, but parties have carried out their own surveys.
Di Maio said he had read one showing the group could manage to form a parliamentary majority - an outcome that public polls have suggested is within reach only of the center-right.
Rightist leaders accidentally revealed fears on Thursday that a 5-Star triumph in the south could endanger their chances.
"They are doing really well, really well," Giorgia Meloni, head of Brothers of Italy, told her allies at a joint rally in a private conversation that was picked up by an open microphone.
Raffaele Fitto, head of the tiny "We're With Italy" party, added that support for the PD was "collapsing" in the south.
"Oh God," said Matteo Salvini, leader of the anti-Europe, anti-immigration League, adding he hoped support for the PD remained above 20 percent to help hold off 5-Star.
At Friday's rally, comedian Beppe Grillo, who founded 5-Star in 2009 in protest against a cronyistic political class, acknowledged the more moderate stance the movement has taken under Di Maio, but said it should remember its roots.
"Even if we go there and do amazing things, we have to remember our hearts, what drove us, the big speeches, the fighting talk," he said.
Party leaders have all ruled out any post-election alliances with rivals. However, Italy has a decades-long history of finding a way out of political stalemate and financial markets appear little concerned by the prospect of a confused result.
Prime Minister Paolo Gentiloni, a PD heavyweight, warned on Friday that Italy's recovery could be derailed by the outcome of the vote and cautioned against the rise of populists.
Party leader and former premier Matteo Renzi told RAI TV he "preferred to be in opposition than be allied with extremists".
Closing the campaign in his home city of Florence, Renzi said: "If you want to vote for fear, anti-politics and anger, don't vote for us."
The PD may benefit from data released on Friday that confirmed the euro zone's third-biggest economy is on the upswing, and from the industry ministry's successful bid to save 500 factory jobs. [nR1N1C4015] [nL8N1QA6RJ]
But a PD official attending the event said on condition of anonymity that the party was "very worried" it might lose seats in the region around Florence, its traditional stronghold.
The center-right bloc has agreed that whichever of its parties wins the most seats will pick the prime minister. In another aside picked up by the microphone on Thursday, Meloni told Salvini that the League would beat Berlusconi's Forza Italia (Go Italy!).
Berlusconi, 81, has served as Italy's prime minister four times but is barred from holding public office until 2019 because of a 2013 tax fraud conviction.
He said on Thursday that his choice to head any future government would be European Parliament President Antonio Tajani, a moderate figure who would reassure EU capitals alarmed by anti-European rhetoric from Berlusconi's allies.
Campaigning is banned on Saturday. Voting runs from 7 a.m to 11 p.m. (0600-2200 GMT) on Sunday, with exit polls released when balloting ends.
However, the possibility of deadlock and the complex calculations required by a hybrid proportional/first-past-the-post electoral law mean it may be many hours before a precise count of parliamentary seats is available.
(Additional reporting by Crispian Balmer, Silvia Ognibene and Steve Scherer; Editing by Raissa Kasolowsky and Matthew Lewis)