ROME — Italian lawmakers elected Sergio Mattarella, a constitutional court judge and veteran centre-left politician, as president on Saturday, handing a welcome political victory to Prime Minister Matteo Renzi.

After three inconclusive rounds of voting this week in which a two-thirds majority was needed, Renzi's candidate Mattarella was elected in the fourth round, when the required quorum fell to a simple majority.

As the ballots were counted out loud in the Chamber of Deputies, the 1,009 parliamentarians and regional officials eligible to vote burst into applause when Mattarella's name surpassed the 505-vote threshold needed, making him Italy's 12th president since World War II.