Italy's main rivals agreed Wednesday on a presidential candidate, a key step towards ending a post-election impasse that has left the country without a government for close to two months.
Centre-left leader Pier Luigi Bersani, whose Democratic Party won February elections by a whisker, emerged from talks with the name of Franco Marini.
Right-wing former prime minister Silvio Berlusconi gave his crucial backing to the 80-year-old former senate speaker but Bersani's choice was met with opposition from within his own party.
"Franco Marini is the candidate best-placed to achieve the greatest consensus," Bersani said after the key talks, involving lawmakers and regional representatives.
"He is a clear-sighted and generous person, one of those who laid social and labour foundations for the centre-left," he said.
"Franco Marini is a positive and serious person and we don't see this as a defeat," Berlusconi said during a meeting with his party shortly after the negotiations.
Marini, a pipe-smoking veteran trade unionist and prominent Christian, headed the Italian senate from 2006 to 2008.
His name came as somewhat of a surprise, with the most frequently mentioned on the rumour mill prior to the talks two former prime ministers -- Giuliano Amato and Massimo D'Alema.
Marini was not yet guaranteed to succeed 87-year-old Giorgio Napolitano however, with Bersani's main rival in the Democratic Party, Matteo Renzi, warning a faction could break ranks.
"I think many people will refuse to vote for him" on Thursday, the Florence mayor said.
The election could take a single day or several, with a two-thirds majority required in the first three rounds of voting and a simple majority thereafter.
Analysts hope this could in turn be the basis for a long-delayed agreement on a new government for the eurozone's third largest economy.
The main centre-left coalition won a general election on February 24-25 but only by a tiny margin and it failed to get enough votes for an overall majority in parliament.
Bersani has tried to woo lawmakers from a new anti-establishment party, the Five Star Movement, but has been rebuffed.
Bersani has ruled out the most obvious alternative -- a grand coalition with Silvio Berlusconi's centre-right -- which would prove hugely controversial among leftists fiercely opposed to the scandal-tainted billionaire tycoon.
The Five Star Movement predicts a right-left agreement and the party's flamboyant leader Beppe Grillo, a former comedian, has already said the move would be "suicide" for Bersani.
He poured scorn on the choice of Marini for president, arguing it was evidence that Bersani was already making "backroom deals" with Berlusconi.
The question of whether or not to strike a deal with Berlusconi has threatened to split Bersani's Democratic Party but is appearing increasingly likely -- according to observers on the eve of the voting.
Berlusconi has said there should be new elections if there is no cross-party deal with Bersani and opinion polls indicate that he would win, although they show he would still fail to get a majority.
While the presidency in Italy is a mostly ceremonial post, it takes on critical importance during times of political crisis, as shown by Napolitano's manoeuvring to put Mario Monti in power when Berlusconi was ousted in 2011.
Big business and trade union leaders have urged politicians to strike an agreement, warning that there is no time to lose as Italy endures its worst economic recession since the post-war period.
Giorgio Squinzi, head of the main employers' association Confindustria, has said the protracted political crisis has already cost the economy around 1.0 percent in gross domestic product (GDP).
The Catholic Church, which remains influential in Italy, has also upped the pressure.
Giovanni Guzzetta, a constitutional expert at Tor Vergata university in Rome, said: "Once the president is elected, we will understand who is going to be in the government."