Former Italian prime minister Romano Prodi was proposed on the weekend as Italy's next president by leftist loyalists -- drawing immediate indignation from Silvio Berlusconi and others on the right. "I find it intolerable that some people think of excluding Prodi" from the list of candidates to succeed outgoing President Giorgio Napolitano in an election in parliament starting Thursday, said Nichi Vendola, one of the influential centre-leftists backing his candidacy. Vendola's comment came a day after Berlusconi, who is angling to become prime minister once again despite a political deadlock, roused his supporters in a chorus of boos against Prodi, saying: "If it's him, better we all leave the country." Berlusconi sees Prodi, who twice beat him in past legislative elections, as his political nemesis and wants to do everything to prevent him becoming head of state. But Prodi, who also headed the European Commission from 1999 to 2004, is also on a preliminary list of possible presidential candidates chosen by members of the anti-establishment, eurosceptic Five Star Movement headed by Beppe Grillo. While the post of presidency is largely symbolic, it holds greater significance now, with Italy's executive branch of government stalled by inconclusive February elections. The centre-left got the most votes but failed to get enough for an overall majority in parliament, with Berlusconi's grouping coming in a very close second, and Grillo's movement third. "The vetoes against Prodi are inacceptable on both the left and the right, given his first-class international profile," said Graziano Delrio, a high-ranking member of the centre-left Democratic Party. "The presidency has become the institution that guarantee Italy's credibility because of the general mistrust of our political class," Delrio said.