ROME (AP) - Italian lawmakers began voting on Thursday for their nation's new president, a step towards resolving the political impasse that has blocked formation of a new government for two months.

Political parties have sparred for weeks over suitable candidates to succeed Mr Giorgio Napolitano, whose term expires next month, but centre-left leader Pier Luigi Bersani and centre-right leader Silvio Berlusconi have reportedly now reached agreement.

The presidency is a largely ceremonial post but with powers that include dissolving parliament and calling new elections. The president, traditionally a widely respected figure supposed to be above the political fray, can also play a critical role in fostering national unity, which could prove vital now as politicians squabble over how to rebuild Italy's recession-mired economy.

Former long-time centrist union leader and ex-Senate president Franco Marini is widely reported to be the consensus choice. But Mr Bersani's party is largely split, and the third biggest force in parliament, the anti-establishment 5-Star Movement led by comic Beppe Grillo, is pushing another candidate, a constitutional law expert.

The bickering over the presidential candidate reflects the divisions that lawmakers have been unable to overcome since the Feb 24-25 national elections that saw the centre-left win control of the lower Chamber of Deputies but fail to do so in the Senate.

Mr Bersani has repeatedly rebuffed an offer from media mogul Berlusconi to form a "grand coalition" government in a bid to stave off new elections.

The new president will sound out political leaders to see who commands enough votes in parliament to try to form the new government, a process that could last weeks.

Mr Napolitano earlier asked Mr Bersani to see if he could secure the necessary support, but Mr Bersani came up short. Voting in joint session for president are both the lower and upper chambers of parliament plus regional representatives. A two-thirds majority is required in the first three rounds of balloting; after that, a simple majority can elect the head of state. The vote could take several days.