Italy's PM Silvio Berlusconi has won a vote of confidence in the Senate but must now face a second vote in the lower house.
The vote is expected to be extremely close and if Mr Berlusconi loses, it could spark early elections.
On Monday, Mr Berlusconi urged MPs not to jeopardise the country's stability by ousting him.
But his critics say he is too mired in personal scandal and corruption allegations to remain in office.
Mr Berlusconi, 74, is halfway through a five-year term but his position has been weakened by the series of scandals, largely involving his relationships with women.
He has also lost the support of his former closest political ally, Gianfranco Fini, along with dozens of his supporters, depriving him of his automatic majority in the lower house.
Italy's high youth unemployment, budget cuts and a crisis over refuse collection in Naples have added to his problems.
The BBC's Duncan Kennedy in Rome said Mr Berlusconi appeared looking very serious in the Senate as the final speeches were made, although his victory was almost certain.
The result was announced slightly earlier than expected, with Mr Berlusconi winning 162 of the 309 votes - 11 senators abstained.
But victory in the lower house is less certain and could come down to one or two votes. He may decide to resign before the second vote goes ahead.
Correspondents say that even if he does win and manages to convince MPs to broaden the base of his coalition, it will be difficult for Mr Berlusconi to continue to govern with only a one or two-vote majority in the Chamber of Deputies.
'Crisis in the dark'
Mr Fini says Mr Berlusconi's personal scandals, gaffes and failed policy programme make his position untenable.
He says he has enough votes to unseat Mr Berlusconi, but the numbers are so close it is not clear which way parliament will go.
In speeches on Monday, the billionaire media tycoon said those seeking to remove him would be unable to form a government, and warned that early elections could cause political instability which would lead to a Greek or Irish-style economic crisis.
"I understand those who would challenge the government, opening a crisis leading to fresh elections or at least proposing a different prime minister, while being sure of the ability to form a new governing majority," he said.
"However, I cannot understand the spirit of those who want to trigger, at all costs, a crisis in the dark."
He said that under his government Italy had gained a good reputation despite the financial crisis.
"I can say with absolute certainty that Italy is not part of the economic problems in Europe - it has become part of the solution," said Mr Berlusconi.