Silvio Berlusconi has survived a vote that could have brought down his rightwing government, but faces a second confidence motion in the lower house this afternoon.

Berlusconi's coalition comfortably won the vote in the senate, the upper house of the Italian parliament, by 162 votes to 135. But its path was smoothed by the rebel group loyal to his former deputy, Gianfranco Fini, which opted for tactical abstention.

The media tycoon's chances of winning in the chamber of deputies, however, became more uncertain this morning when three heavily pregnant deputies all said they would be in parliament to cast their votes against the government. Federica Mogherini of the Democratic party, Italy's biggest opposition group, told her chief whip she would arrive at midday local time when the division is due.

"Unless my water breaks now, I shall be in the chamber on time," her chief whip quoted her as saying. Two other pregnant deputies who have supported Fini's revolt also said they would vote. One, Giulia Cosenza, was brought to parliament in an ambulance. The other, Giulia Bongiorno, was taken into the chamber in a wheelchair.

Adding to the drama, thousands of demonstrators were expected to converge on the centre of Rome to register their protest against Berlusconi's government. Police vans ringed the prime minister's official residence and blocked both ends of the street that leads past his private home.

Facing a potential split among his followers, Fini agreed on Monday to a convoluted compromise that included an invitation to Berlusconi to resign after winning the vote in the senate. Hence this morning's abstention.

The rebels said they would then be ready to back the prime minister if, after resigning, he assembled a new government with a new programme that acknowledged their demands. Fini and his supporters, who split from the government's parliamentary majority in July, advocate a more progressive form of conservatism that allows for greater internal party democracy.