Italian Premier Romano Prodi resigned Thursday night after his government lost a risky Senate confidence vote.

The center-left government fell four votes short of the 160 needed for victory. The vote was 161-156.

Elected in April 2006, Prodi has had a shaky government from nearly the start. But it lurched toward collapse after a small Christian Democrat party, whose votes were vital to a coalition majority in the Senate, yanked its support earlier this week in the latest squabbling among his allies.

Calling early elections or asking a politician to try to form another government are among President Giorgio Napolitano's options as head of state.

The Presidential Palace said Napolitano would start consulting Friday with political leaders to help him decide