Italian lawmakers failed for a third time to elect a president yesterdaybut Prime Minister Matteo Renzi looked likely to see his candidate, a senior judge, prevail today when the number of votes required will be lower.

Renzi’s Democratic Party (PD) and a handful of allies have pledged to back Sergio Mattarella, 73, a low-profile constitutional court judge and a veteran centre-left politician who is little known to most ordinary Italians.

Any failure by Renzi, who has been in office less than a year, to get Mattarella in would suggest his authority over his party is wavering, raising the spectre of an early national election.

With newly-elected Greek Prime Minister Alexis Tsipras facing tricky talks with German-led European partners on renegotiating Greece’s debt mountain, a political crisis in Italy would compound uncertainty in the eurozone.

Though a largely ceremonial figure, the Italian president wields important powers at times of political instability, a frequent scourge in Italy, when he or she can dissolve Parliament, call elections and pick prime ministers. Three votes on the president – one on Thursday and two yesterday – have so far failed to produce a president, but the real test for Renzi was always going to be in the fourth round today.

That is when the quorum required falls to a simple majority, or 505 of the 1,009 parliamentarians and regional officials eligible to vote, rather than the two-thirds majority needed in the first three rounds.

On paper Renzi should have the numbers to elect Mattarella, but voting by secret ballot in Italy has a history of intrigue and unpredictability. Two years ago, two candidates ostensibly backed by the PD fell short due to anonymous defections within party ranks.

By picking Mattarella, Renzi has angered centre-right leader Silvio Berlusconi, who accuses him of betraying what the media tycoon said was a promise to give him a role in choosing the candidate as part of a pact the two leaders made last year to draft institutional reforms together.

Renzi has also irked his small New Centre Right party coalition partner which also complains that it was not consulted. But he appears to have united his own party, many of whom oppose his alliance on reforms with Berlusconi.