* Monti, Bersani aim for "maximum covergence"
* Voting by parliament, regional delegates begins Thursday
* Prodi, Amato possible candidates but no clear favourite
Outgoing Italian Prime Minister Mario Monti and centre-left leader Pier Luigi Bersani moved closer to agreement on Monday on choosing a new president, a vital step to ending the stalemate created by an inconclusive election in February.
Seven weeks after the general election, which left no party with a viable majority in parliament, Monti remains head of a caretaker government with vital reforms on hold until a new administration can be formed.
The divided parties are due to begin voting on Thursday to choose a successor to President Giorgio Napolitano, whose mandate expires on May 15.
On Monday Monti met Bersani, whose centre-left alliance won the largest share of the vote in February but fell short of the numbers in parliament needed to form a government.
He said he had agreed with Bersani to seek "the maximum possible convergence of opinion among the political forces on the choice of an authoritative candidate who would be able to represent national unity."
Under constitutional rules, Napolitano no longer has the power to dissolve parliament, meaning it will be up to his successor to find a way out of the impasse, either by coaxing parties into an agreement or by calling fresh elections.
The head of state has an important ceremonial function but also has a broadly defined role in overseeing government, as Napolitano himself demonstrated during the financial crisis which brought in Monti's technocrat government in 2011.
Already the parties have been engaged in backroom discussions to try to settle on a candidate short list.
A succession of possible names has been mooted but no clear favourite has emerged and the wrangling that has already broken out suggests there will be a fierce battle to select a figure meant above all others to symbolise national unity.
Whether or not they can bring in Silvio Berlusconi's centre-right alliance or the anti-establishment 5-Star Movement, an accord between Monti and Bersani would be significant because their two combined blocs would theoretically have the numbers to elect a president on their own.
Among the candidates that have already been suggested, former prime ministers Giuliano Amato, Romano Prodi and Massimo D'Alema and former European Commissioner Emma Bonino have been most talked about in the press.
However all have also drawn objections, with Prodi ruled out by Berlusconi, Amato and D'Alema both viewed with misgivings as representatives of the traditional political elite and Bonino seen as hostile to the still-powerful Catholic church.
Under the voting procedure, a two-thirds majority of 1,007 electors from the combined houses of parliament plus regional delegates is sought. If that cannot be reached in three rounds of voting, a further round can be held in which only a simple majority is required.
Bersani, who won control of the lower house but fell short of the Senate numbers which would have given him an overall parliamentary majority, has failed in his attempts to form a government.
He has been rebuffed by 5-Star leader Beppe Grillo and refuses to share power in a "grand coalition" with Berlusconi who has also demanded a say in choosing the next president.
While he and Monti between them may have the numbers to elect the president alone, they may be reluctant to weaken the authority of the next head of state by forcing an election over the objections of the centre-right, which won almost as many votes in the election as the centre-left.