* New tests for Berlusconi after electoral losses
* Northern League promises support for now
* Belt tightening package prepared amid calls to cut taxes
By Deepa Babington
ROME, June 20 (Reuters) - Italian Prime Minister Silvio Berlusconi faces parliamentary votes this week that will test the strength of his coalition, struggling to stay united after two crushing electoral losses in the past month.
A string of corruption cases, a stagnant economy and a sordid scandal involving an underage prostitute have taken their toll on Berlusconi, whose support among voters stands at a record low of 29 percent, according to pollsters IPR.
The prime minister is expected to win a confidence vote on Tuesday over measures to help growth and a likely vote on Wednesday to see if the government still enjoys a majority after his main ally, the Northern League, promised its support.
But the centre-right coalition remains in a precarious position, with voter support at record lows, a revived left and infighting that has pitted an increasingly frustrated League against an economy minister keen to rein in public finances.
In a reminder of risks facing Italy, ratings agency Moody's on Friday said 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.
The government has pledged to present a package of measures in the next few weeks worth around 40 billion euros (${esc.dollar}57 billion) to eliminate the budget deficit by 2014, a task made even more arduous by the demands of some coalition members to cut taxes.
Berlusconi, embarrassed by a stinging defeat in local elections followed by further setbacks in referendums this month, has tried to put on a brave face ahead of the votes.
"Today Italy needs to be governed, needs stability," he told reporters in Milan on Sunday. "There is no doubt that the coalition will win the confidence votes in parliament."
Analysts say the government will scrape through the votes, but the coalition risks stumbling from one crisis to the next.
"Political uncertainty remains an issue. The government led by PM Berlusconi is losing appeal," Barclays Capital analysts wrote in a research note on Monday.
"We do not think the Northern League will trigger a political crisis in the short term. That said, this is a possibility which cannot be entirely ruled out. Political uncertainty is likely to remain until the end of the legislature (2013), in our view."
SEX SCANDALS TO REFERENDUM BLOWS
After Tuesday's confidence vote in the lower house of parliament, the following day the same chamber will vote to verify whether the government has a majority.
This was demanded by President Giorgio Napolitano after new ministers were appointed in May, part of a process to change the make-up of the ruling coalition after defections by followers of Gianfranco Fini, Berlusconi's former ally and now bitter rival.
The government is expected to sail through a similar motion on Tuesday in the Senate, where it enjoys a large majority.
Berlusconi is expected to address both houses, outlining his government's program for the remainder of its term, including concessions to placate the League.
The pro-devolution, anti-immigrant League has been a loyal Berlusconi ally over the years but triggered the collapse of the media magnate's first government in 1994.
At its annual gathering in Pontida on Sunday, League leader Umberto Bossi promised not to pull the rug from the under the government now but issued an ultimatum to push through tax cuts and cut back on costly foreign missions in Libya and elsewhere.
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 Fini last year that cost him a guaranteed majority in parliament.
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, which was followed by defeats in referendums on nuclear energy, water privatisation and trial immunity for government ministers.
(Editing by Michael Roddy)
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