Italian Prime Minister Silvio Berlusconi's government will face a vote of confidence this week.
If Mr Berlusconi loses the vote, his government will fall, probably leading to a general election that could be held as soon as late June.
Mr Berlusconi has been in trouble since the centrist Union of Christian Democrats (UDC) quit his government on Friday demanding he make sweeping changes after the centre-right suffered a bruising defeat in regional elections two weeks ago.
His situation looked even weaker today as another party in his four-way coalition, the much bigger National Alliance, also began to debate whether it too should pull out.
"Berlusconi is clutching on to his own leadership, determined to impose his own timing and his own ambitions on parliament, on the president and on the country," said the mainstream Corriere della Seradaily in an editorial on Tuesday.
Yesterday, Mr Berlusconi performed what Italian media described as a classic piece of political theatre, apparently agreeing to the UDC's demand to resign and present a new government, only to turn around a few hours later and say he had no such intention.
Italian politics now moves into largely unchartered territory, with Berlusconi apparently daring the UDC to vote him out of office.
The UDC has promised "external support" for the government and may vote to keep Mr Berlusconi in power, avoiding an election that polls say would hand government to the centre-left led by former European Commission President Romano Prodi.