| Silvio's supporters moved a confidence motion before a no-confidence vote due to be held in the lower house [AFP]
Scuffles have broken out in Italy's parliament during a no-confidence vote against Silvio Berlusconi, Italy's prime minister, after a lawmaker broke ranks with her party and voted in favour of the government.
The voting session in the lower house was briefly interrupted on Tuesday after Katia Polidori voted in favour of Berlusconi, sparking jeers.
The vote is expected to go down to the wire. Polidori is a member of the group of lawmakers loyal to Gianfranco Fini, the Chamber speaker who broke with Berlusconi this summer, precipitating the political crisis. Voting resumed soon after.
Berlusconi, 74, survived a confidence vote in Italy's Senate on Tuesday morning, but the Chamber of Deputies vote was riskier and was expected to come down to a handful of swing votes.
Although Berlusconi has previously defied critics, winning three elections since 1994 despite a string of gaffes and scandals, he has been weakened recently by the breakup with Fini, which cost him a parliamentary majority.
Single vote may decide
The vote in the lower house could be decided by as little as a single vote, political commentators have said.
Analysts have estimated that Berlusconi may just have the numbers to survive with 314 possible votes against 313 for the combined opposition.
Nazanine Moshiri, Al Jazeera's correspondent in Rome, said police were prepared for protests in the event that Berlusconi wins the afternoon vote.
"We are expecting protests. The whole area around [parliament] has been fenced in by police because we understand that students, if Berlusconi does win this vote, are going to try and storm parliament," she said.
In an address to parliament on Monday, the prime minister said: "If the government has to operate well, it must be left to people to decide and this is part of our constitution and sovereignty.
"If this principle is violated, then it means that the spirit has been betrayed. And those in parliament have to interprete the wish of the people."
The vote comes as Berlusconi - accused of paying for sex and paying the Mafia to protect his family and busines interests - wades through one of his toughest years in 2010.
A split with a group led by Fini in July cost him a secure parliamentary majority and after months of stalemate, a no-confidence motion in parliament seems likely to be decided by just one or two votes.
Guido Moltedo, a political commentator in Rome, told Al Jazeera that the vote was a "turning point" for Italy "even if Berlusconi succeeds in having a majority [of the vote]".
"Everything is going to change ... in this country; and the confusion will be great according to me in both cases: if Berlusconi wins a majority or if he loses the confidence vote," he said.
"Berlusconi can go away in the near future but the situation is the country will not be much better ... because the opposition is fragmented and fractious."
The prime minister has been predicting he will win, but if he loses he will have to resign, halfway through the five-year term of parliament.
The result may depend on last-minute changes of heart or outside factors such as whether any of three pregnant deputies expected to vote against the government have to be absent from the chamber.
The vote will be closely watched on bond markets which are on high alert over the euro zone debt crisis and which could turn on Italy, one of the most heavily indebted countries in Europe, if the situation threatens financial stability.
Even if Berlusconi scrapes through, there is little confidence that he will have the strength to push through the kind of reforms authorities such as the Bank of Italy believe are needed to address deep-seated problems in the economy.
Al Jazeera and agencies