ROME (Reuters) -Italy's centrist Azione party will enter an alliance with the larger Democratic Party in next month's national election, an Azione party source said on Tuesday, in a move seen boosting the centre-left's chances in the vote.
Italy's election law favours parties that form broad alliances. The ballot is set for Sept. 25 and polls show a conservative alliance is on course for victory.
"Deal done," the Azione party source said after a meeting between its leader Carlo Calenda and PD boss Enrico Letta.
Azione is a small party, polling only around 5-7% in surveys, but two senior members of Silvio Berlusconi's Forza Italia defected to it last week, saying Italy's conservative bloc had become too extremist.
Forza Italia is part of an alliance with the League and far-right Brothers of Italy party that is seen on course for electoral victory.
(Reporting by Angelo AmanteWriting by Keith WeirEditing by Agnieszka Flak)