Beppe Grillo, the founder of the anti-establishment 5-Star Movement, talks during a march in support of the 'No' vote in the upcoming constitutional reform referendum in Rome
ROME (Reuters) - Italy's anti-establishment 5-Star Movement, benefiting from a schism in the ruling Democratic Party (PD) and division in the centre-right, has built a commanding lead over its rivals, an opinion poll showed on Tuesday.
The Ipsos poll in Corriere della Sera newspaper put the 5-Star, which wants a referendum on Italy's membership of the euro, on 32.3 percent - its highest ever reading and 5.5 points ahead of the PD, which was on 26.8 percent.
The third-largest party was the anti-immigrant Northern League on 12.8 percent, with Silvio Berlusconi's Forza Italia (Go Italy!) on 12.7 percent.
The PD appeared to be paying the price for its internal feuds, dropping more than three percentage points in a month, as former prime minister Matteo Renzi battles to reassert his authority following a walkout by a faction of left-wingers.
Italian parties are still trying to draw up a new electoral law, with political analysts expecting them to agree on some form of proportional representation that might reward a stable majority to any group that wins at least 40 percent of the vote.
The Ipsos poll suggested that both the traditional centre-left and centre-right blocs would fall well short of the 40 percent threshold, leaving the 5-Star in the driving seat.
However, the party, founded by comic Beppe Grillo, has repeatedly ruled out forming an alliance with other groups, suggesting Italy could face political instability following the next national election, which is due by early 2018.
(Reporting by Crispian Balmer; Editing by Philip Pullella)