By Deepa Babington
ROME (Reuters) - Italian Prime Minister Silvio Berlusconi on Tuesday overcame coalition infighting to win a vote of confidence, his first parliamentary test since suffering two stinging electoral losses.
Berlusconi's center-right government won the lower house vote on measures to boost growth by a margin of 24 votes, thanks to its Northern League ally that promised support despite defeat in referendums and local elections over the past month.
The motion passed with 317 deputies voting in favor and 293 against. Two lawmakers abstained.
The victory is likely to provide only brief respite for Berlusconi, who faces plummeting approval ratings, squabbling allies and a faltering economy.
His coalition remains in a precarious position, with an increasingly frustrated League demanding tax cuts and an end to Italy's costly mission in Libya in return for further support.
Asked if Berlusconi would see out the end of his term in 2013, the League's mercurial leader Umberto Bossi said: "If he does the right things, yes. We've already given Berlusconi a timeline."
Center-left leader Pier Luigi Bersani said it was only a matter of time before Berlusconi's coalition collapsed.
"We are one step nearer to the break-up of the center-right, which is getting ever closer," he said.
Berlusconi was expected to address the Senate later on Tuesday, outlining his government's program for the rest of its term, including concessions to placate the League.
A separate vote in the lower house to verify whether the government enjoys a majority may be called on Wednesday.
In a reminder of the risks facing Italy, ratings agency Moody's said on Friday it may cut the country's rating over concerns about its ability to bring down a public debt mountain equivalent to about 120 percent of gross domestic product.
Berlusconi faces a bigger test in coming weeks when he must push through measures worth around 40 billion euros ($57 billion) to eliminate the budget deficit by 2014 -- a task made even more arduous by the League's demand to cut taxes.
Berlusconi managed to wave off a series of sex scandals soon after sweeping to power in 2008. But his fortunes began to wane after an acrimonious split with Gianfranco Fini, his old ally, last year that ended his guaranteed parliamentary majority.
A string of corruption cases, a faltering economy and a scandal involving an underage prostitute have taken their toll on Berlusconi, whose support among voters now stands at a record low of 29 percent, according to pollsters IPR.
The government's sagging support even among its core northern power base was underscored by the loss of the Milan mayoral seat in local elections last month. That was followed by defeats in referendums on nuclear energy, water privatization and trial immunity for government ministers.
(Editing by Jon Boyle)