(By Paul Virgo) (see related stories) Rome, April 20 - Saturday's re-election of President Giorgio Napolitano provoked gratitude from the mainstream Italian parties and protests from followers of the anti-establishment 5-Star Movement (M5S). Most of the parties in parliament lobbied Napolitano to agree to serve a second term and end a situation of gridlock after five ballots failed to elect a successor to the 87-year-old because of rifts within the centre-left Democratic Party (PD), the biggest group in parliament. The deadlock was threatening to further complicate efforts to end the political impasse recession-hit Italy has endured since February's inconclusive general election. Ex-premier Silvio Berlusconi, whose centre-right alliance came second in February, thanked Napolitano for his "spirit of sacrifice" and "personal generosity" for agreeing to serve a second term as Italy's head of state "in such a difficult, uncertain situation". Outgoing PD leader Pier Luigi Bersani said the re-election was "excellent" and outgoing Premier Mario Monti expressed satisfaction too. But there was tension outside Italy's Lower House of parliament, where a big crowd gathered after M5S leader Beppe Grillo urged "millions" to protest against the re-election. "I'm going to Rome. I'll be outside the House," comedian-turned Grillo said via Twitter. "There must be millions of us". Earlier Grillo said on his blog, which gave life to the Internet-based M5S in 2009, that the other main parties' decision to ask the 87-year-old to stay on a head of state amounted to a "coup". He accused the established parties of making secret deals behind closed doors, unlike the M5S, which chose its presidential candidate, Constitutional Lawyer Stefano Rodota', after an online vote of members. Grillo said he was immediately abandoning a campaign in the north of Italy to drive 650 km to the Rome parliament. But he then announced he would not be in the capital in time to lead the protest on Saturday and made an appeal for the there to be no violence. The crowd outside the House, which was not just made up of M5S supporters, shouted "buffoons", "Rodota" and "come on out" after it was announced that Napolitano had been re-elected. Grillo's comments were blasted by mainstream politicians, with some saying the protest was similar to Fascist dictator Benito Mussolini's "march on Rome" in 1922. "Mussolini and Hitler said the same things as Grillo," said Northern League chief and Lombardy Governor Roberto Maroni. "Parliament is the seat of democracy". Rome Mayor Gianni Alemanno told Grillo to "calm down". "I don't like the idea of threatening parliament," Alemanno added. "Grillo should respect Rome". Ex-premier Silvio Berlusconi expressed concern too. "We've seen all sorts (from the M5S) and now there is Grillo's comical march on Rome and his funny fascism," said Berlusconi. "It's a farce that should make us laugh, but also make us reflect on how this movement with no democracy may develop". Rodota' also distanced himself from the protest, saying that parliamentary decisions should be contested within "democratic, Constitutional legality". European Commission President Jose' Manuel Barroso was among the first international figures to welcome Napolitano's re-election. "I'm certain that under the new presidency Italy will continue in its European tradition to give a decisive contribution to our common European ideal," said Barroso.