Rome, April 16 - Beppe Grillo, the head of Italy's anti-establishment 5-Star Movement (M5S), said that he could be open to some sort of political collaboration with the Democratic Party (PD) if it supports the movement's candidate to succeed outgoing Italian President Giorgio Napolitano, whose mandate expired Monday. In his blog, Grillo invited PD leader Pier Luigi Bersani to vote for Milena Gabanelli, an outspoken and highly respected investigative journalist, to succeed Napolitano. Gabanelli, known for her hard-hitting investigative television news program Report, won the most party votes in an online primary on Grillo's blog. Grillo said the choice of Gabanelli was "in harmony" with the movement itself. In his appeal to Bersani, Grillo said that if the PD leader voted to support Gababelli's candidacy it might lead to collaboration between the movement and the center-left party, which won the most votes in the lower house in February's inconclusive national elections. "Think about it Bersani, think about it. It could really be the beginning of a - who knows? - collaboration. Try. Try to vote for her," he said. "Let's start from there. Then we'll see: electoral reimbursements, an anti-corruption law, making ex-premier Silvio Berlusconi ineligible. Maybe we could find consensus". However the comedian, whose movement emerged as the surprise kingmaker in the February elections, also made clear that he might look elsewhere for allies. Grillo said that if he couldn't find a friendly ear with the PD leader, he might try with the PD's younger leaders - an obvious nod to Matteo Renzi, the 38-year-old mayor of Florence and PD rising star who has made repeated jabs at Bersani in recent days over his handling of the gridlock. Separately, keeping his battle against Berlusconi going, Grillo on Tuesday said that the leader of the PdL "is a corpse brought back to life and Rome is the cemetery of democracy". Speaking at a rally, Grillo said that his worry "is the fact that there are still several million people who voted for (Berlusconi), while he ridicules them".