The foreign policy program presented by Foreign Minister Massimo D'Alema in Prodi's new center-left government, who came to power in May 2006, was two votes short of the required 160. Three out of nine parties in the ruling coalition refused to back Italian troops' further stay in the U.S.-led peacekeeping contingent in Afghanistan.
At 7 p.m. local time (6 p.m. GMT), Italian President Giorgio Napolitano will meet with Prodi to decide the government's future, the presidential press service said. D'Alema said Tuesday under the constitution the Cabinet would have to resign if the Senate's ruling majority failed to back the motion.
Leaders of opposition parties, which immediately demanded the resignation of the Cabinet, have gathered for consultations with the opposition leader and ex-premier, Silvio Berlusconi, while Prodi is talking with key ministers and heads of parliamentary factions.
The ruling coalition was split over the Afghanistan issue, with the Communist Refoundation Party, the Party of Italian Communists and the Federation of the Greens favoring withdrawal of Italian troops.
On January 26, the Italian government decided to renew funding for the Italian troop deployment as part of NATO's force in Afghanistan.
D'Alema made Afghanistan the key point of his speech in parliament earlier Wednesday, saying Italy had to stay in the country to meet its obligations to the U.S. and to avoid international isolation.
Justice Minister Clemente Mastella said the vote in the Senate was unlikely to lead automatically to the government's resignation, because it was a resolution and not a vote of confidence that had been put to vote.
"It is not a classical political crisis - it is a rift among left-wing parties," he said, adding that the government should either be subjected to a vote of confidence or signatures should be collected in support of the Cabinet.