Italy's main parties appealed to President Giorgio Napolitano on Saturday to stay on and help resolve a deepening political crisis after they failed to elect his successor in five rounds of voting.
Political leaders said it was "necessary and urgent that parliament show unity and national cohesion with the re-election of President Napolitano," the presidency said in a statement.
The politicians voiced concern over a "grave situation", it said, adding that Napolitano's response would come by 1300 GMT just before another round of presidential voting in parliament.
Prime Minister Mario Monti's party Civic Choice said the outgoing premier "pleaded with President Napolitano to re-propose his candidacy... in the higher interest of the country".
The 87-year-old has previously said he intends to retire as his seven-year mandate comes to an end but he is seen as an important guarantee of stability in an increasingly confusing situation.
Elections two months ago proved inconclusive and the centre-left, which narrowly won the election but failed to get enough votes for a majority in parliament, has been in total disarray.
The leadership of the leftist Democratic Party -- secretary Pier Luigi Bersani and chairwoman Rosy Bindi -- resigned on Friday after two presidential candidates it proposed failed to get elected.
Ex-trade union leader Franco Marini and widely respected former European Commission chief Romano Prodi have both now withdrawn their candidacies, and the top-selling Corriere della Sera daily said the country was "suspended in a void".
In a fifth round of voting earlier on Saturday, the largest number of ballots cast were spoiled -- a stalling tactic as political parties try to find a way out of the impasse.
Prodi lost on Friday after 101 lawmakers from the centre-left rebelled against their leadership and did not vote for him -- a sign of deep divisions.
"Collective Suicide", read the headline of an editorial in Il Fatto Quotidiano daily, adding that the PD was "in tatters".
La Repubblica said Prodi's failed candidacy was "a disaster" for the party, which was formed in 2007 as an amalgam of various centrist parties and the remnants of the powerful Italian Communist Party.
"The epicentre of the crisis is the Democratic Party," it said, accusing rebels from the centre-left of "blind cannibalism" and blaming the "mediocrity of the party leadership".
Bersani had been the target of growing criticism after he threw away a big lead in the opinion polls ahead of the February elections.
The eurozone's third largest economy has been in political deadlock since then with politicians unable to strike a compromise to form a government as Monti's outgoing cabinet limps on with only interim powers in the middle of a steep recession.
The big business lobby Confindustria has warned that Italy has already lost one percentage point in gross domestic product (GDP) since the political crisis began, although reaction from the financial markets has been relatively muted.
Observers had voiced hope that a cross-party agreement on a new president could have been the basis for a broader deal on forming a new government. But that now appears a distant prospect and fresh elections are more likely.
Among the remaining possibilities for president is Interior Minister Anna Maria Cancellieri, who has been proposed by Monti and would be the country's first female head of state or government.
The names of former prime ministers Giuliano Amato and Massimo D'Alema are also frequently mentioned.
For its part, the anti-establishment Five Star Movement party, which won a quarter of the vote in the February elections, has put forward Stefano Rodota -- an academic and civil rights advocate.