Italy's president holds crisis talks with political leaders on Thursday to see if Romano Prodi, who has resigned as prime minister after nine months in power, can still head a government.
Prodi, who won the narrowest election in Italy's post-war history last year, quit on Wednesday after he was defeated in the Senate on foreign policy -- a constant source of friction in his nine-party, Catholics-to-communists coalition.
Under the constitution, President Giorgio Napolitano must find a way out of the impasse and hold consultations with party and parliamentary leaders as well as former presidents.
There are three main scenarios.
<b1>If Napolitano finds enough support for Prodi among center-left parties, he could ask him to either form a new government or go to parliament with his present cabinet for a confidence vote. If he won that, he could remain in office.
If support for Prodi is not strong enough for him to carry on as prime minister, Napolitano could ask someone else, possibly Interior Minister Giuliano Amato, to form a caretaker government of experts with cross-party backing.
If no agreement is found on who should be prime minister, Napolitano would be forced to dissolve parliament and call early elections, even though this option appears unlikely for now.
Analysts said any Prodi government would be extremely weak and vulnerable to infighting among its allies, who disagree on everything from Italy's military missions abroad to gay rights.
"Even if there is another Prodi government it would be hanging by a thread and would not last long, as the reasons for tension abound," said Gianfranco Pasquino, political science professor at the Bologna center of Johns Hopkins University.
Prodi, 67, was heading the 61st Italian government since 1945. After his election last April, he enjoyed a brief honeymoon period but his popularity ratings plummeted as he pushed through a deficit-cutting 2007 budget to bring Italy in line with EU requirements.
Despite bickering within his coalition, his resignation came as a surprise.
The vote in the Senate was intended as a motion of support for the government's foreign policy, but Foreign Minister Massimo D'Alema turned it into a litmus test on the executive's strength, giving Prodi little choice once the motion failed.
Prodi only has a one-seat majority in the Senate, and the revolt of two leftist senators in his coalition was enough to put the government in a corner.
It was deja vu for Prodi, whose last spell in power almost a decade ago was also cut short by far-left coalition allies.
This time they rebelled over keeping Italian troops in Afghanistan and allowing the expansion of a US military base in Italy.