ROME (Reuters) - Italy s ruling Democratic Party (PD) has lost support following its flop in a regional election in Sicily, while Silvio Berlusconi s Forza Italia (Go Italy!) has gained ground, according to a poll released on Thursday. National elections must be held by next May, with all recent opinion polls suggesting that it will end in a hung parliament. IXE pollsters said backing for the center-left PD, which is led by former prime minister Matteo Renzi, dropped to 23.8 percent, down 3.6 percentage points from its last survey in mid-October. The PD slump enabled the maverick 5-Star Movement to establish itself firmly as Italy s most popular party, climbing to 27.9 percent from a previous 27.2 percent. Forza Italia moved into third spot, rising to 15.5 percent from 13.6 percent and jumping ahead of its long-time ally, the far-right Northern League, which dropped 1.6 percentage points to 13.5 percent. Under the terms of an electoral law approved last month, which allows the creation of multi-party coalitions ahead of the national elections, the center-right bloc is expected to emerge from the ballot box as the biggest single force. The bloc won a regional vote in Sicily on Nov. 5, with the victory seen as a personal triumph for Berlusconi, who used the ballot to revive his political career after years of graft trials, sex scandals and ill-health. The 5-Star came second on the Mediterranean island, with the PD limping in a distant third. Renzi s party has been beset by feuding and looks unlikely to reach any pre-election pact with myriad leftist groups, which have accused him of pushing the PD too far to the left. The IXE poll suggested the center-right would take a combined 33.8 percent of the vote. The bloc leaders have said whichever party wins the most votes will decide who should be its prime ministerial candidate. 