ROME (Reuters) - Italy's center-left Democratic Party has increased its lead over the center right ahead of an election expected in March, while the anti-establishment 5-Star Movement of comic Beppe Grillo has slipped slightly, a poll showed on Friday.
The poll by the SWG polling institute showed the Democratic Party (PD) with 30 percent support, up from 26.7 percent a week earlier, as the party's widely-praised primary campaign to choose its main election candidate lifted support.
Grillo's movement, which wants Italy to hold a referendum over whether to stay in the euro, saw its support slip to 19.5 percent from 21.1 percent a week earlier.
Former Prime Minister Silvio Berlusconi's center-right People of Freedom party (PDL), which has plunged into deep crisis and is on the brink of splitting apart, was third at 14.3 percent, down one percentage point from a week before.
Berlusconi's electoral intentions remain unknown after several changes of mind over whether to run or not.
There has been wide speculation that he may set up a breakaway group from the PDL possibly named after Forza Italia, the party he created to launch his political career in 1994.
According to the SWG poll, such a breakaway party might win 9.3 percent, while reducing a rump PDL to around 4 percent.
The new centrist movement led by Ferrari chairman Luca Cordero di Montezemolo, which wants to continue the reform agenda of Prime Minister Mario Monti, saw its support fall to 3.8 percent from 4.8 percent a week earlier.
The PD will need to seek the support of a smaller coalition partner but whether the center left will have enough support to form a stable parliamentary majority will depend in large part on the outcome of a months-long struggle to reform the electoral system which will regulate the ballot.
The current system, which is criticised on all sides, allows party bosses to handpick members of parliament without giving voters any say and rewards the biggest party with a huge winner's bonus, whether or not it gains a majority of votes.
Reporting by James Mackenzie; editing by Andrew Roche