Following weeks of hesitation, Monti declared his availability on Sunday to lead a reform-minded centrist alliance to seek a second term to complete the economic reform program begun when he took office just over a year ago.
The former European Commissioner, appointed at the head of a technocrat government to save Italy from financial crisis, has now thrown off his mantle of neutrality and entered a race that will be dominated by his tough reform agenda.
Even if he confirms his entry into the campaign, Monti appears unlikely at this stage to return to office but his involvement could strengthen a centrist alliance and help shape the agenda of the next government.
The center-left Democratic Party (PD), which has pledged to maintain Monti's broad reform course while giving more help to workers and pensioners and emphasizing growth more, is favored to win but may have to strike a coalition deal with the center.
In an open letter to Italians posted online and accompanied by a 25-page policy program, Monti said he hoped that the agenda would lead to an "open reflection" that would help shape the debate ahead of the election on February 24-25.
He urged a mix of budget rigor and structural reform as well as measures to crack down on corruption and get more women and young people to work.
However the tone of the campaign has inevitably moved away from calm debate and into the murky and sometimes treacherous territory of Italian party politics, where Monti is a novice.
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At a news conference on Sunday, he attacked left-wing trade unions for resisting reform but reserved special criticism for his scandal-plagued predecessor Silvio Berlusconi, whom he picked on repeatedly for his "bewildering" changes of position.
Speaking to one of his own television channels, the 76 year-old media billionaire responded by saying it would be "immoral" for Monti to fight the election after governing as an unelected premier with the support of the main parties.
One of Berlusconi's chief lieutenants, Fabrizio Cicchitto, parliamentary floor leader of his People of Freedom (PDL) party, indicated that Monti's international standing and the respect he enjoys among Italy's European partners would count for little.
"He's taken aim at the PDL, which obviously has no choice but to respond in kind," he said.
Monti, a Life Senator who does not need to stand for election to parliament, has not said exactly what forces he could support but the centrist parties he has been linked with greeted his announcement with great enthusiasm.
"We're not forcing Monti but obviously if it happens, the value it adds to our project will be enormous," Pierferdinando Casini, head of the centrist UDC party, which is close to the Catholic church, told the daily La Repubblica.
A small number of centrists from both the two main parties, including former Foreign Minister Franco Frattini announced they were leaving their parties and would support Monti, whose reform agenda is strongly backed by Italy's business establishment.
However the centrist group lags both the center-left Democratic Party (PD) and the PDL as well as the anti-establishment 5-Star Movement in opinion polls and without Monti, it has little chance of making any significant gains.
Even with the respected economics professor at its head, a centrist alliance including the UDC and other smaller parties including a new group created by Ferrari chairman Luca Cordero di Montezemolo, appears likely to struggle to pass 15 percent.
(Reporting By James Mackenzie; Editing by Jon Boyle)