Italian Prime Minister Romano Prodi has handed in his resignation after his fragile centre left coalition lost a crucial parliament vote.
Italy's President, Giorgio Napolitano, will discuss Mr Prodi's future with political leaders tomorrow before deciding whether to accept his resignation.
The future of the government is now unclear after some coalition partners objected to the planned deployment of 2,000 extra troops in Afghanistan and the enlargement of a US military base in Vicenza in northern Italy.
The Afghanistan deployment and the enlargement of the US base are both strongly opposed by the Greens and Communists who make up part of a coalition which also includes liberal and Catholic parties.
More than 80,000 people took part in a rally last Saturday in Vicenza against the base enlargement.
The government needed 160 votes in the Senate debate to get a formal motion of support. But only 158 senators voted in favour and 136 opposed the government.
Following the vote, opposition leader Silvio Berlusconi led the calls for change, saying Mr Prodi should resign 'immediately'.
Mr Berlusconi was narrowly beaten by Romano Prodi in elections last April.
