Italy is without a leader after Romano Prodi resigned yesterday. He quit after left-wing members of his nine-party coalition voted against the government’s foreign policy.
Mr Prodi’s decision leaves proposed new laws granting gay couples legal protection unresolved.
The coalition lost a Senate motion backing the continued deployment of troops by two votes.
Mr Prodi then met with the President and tendered his resignation.
Italy has 2,000 troops in Afghanistan as part of a multi-national force.
Earlier this month the coalition, which has only been in government since May 2006, agreed to bring forward legislation that would have granted legal recognition for gay and lesbian couples for the first time.
Couples would have been able to formally register with their local authority, and have rights over property and inheritance.
They would also have had the right to visit their partner in hospital.
The bill was expected to have a tough passage through the Italian parliament, but with the collapse of the coalition government it is unclear if the legislation will move forward.
Gay campaigners complained that the proposed “civil pacts of solidarity” are a watered down version of what the coalition government had promised at last year’s election.
Catholic MPs denounced the new bill as an attack on marriage.
The President of Italy is now in talks with political parties to try to find a new coalition.
Mr Prodi remains as a caretaker Prime Minister for the time being.
While MPs in the lower house of the Italian parliament continue to support Mr Prodi, left-wing Senators are responsible for ushering him out of office.
As well as concern over troops serving in Afghanistan, Senators opposed the expansion of a US military base in Vicenza.
Large street protests took place last weekend opposing the American plan to have 5,000 soldiers based there.