ROME — The president of Italy’s Senate is leading a new political force appealing to disaffected Democrats as the nation’s splintered left struggles against a surging populist party.

Pietro Grasso, who was national anti-Mafia prosecutor before entering politics, announced Sunday that Free and Equal, the group he’s leading, will promote reducing social inequality in Italy.

Democrats are the main party in the current center-left governing coalition. But they’ve suffered prominent defections under former Premier Matteo Renzi’s leadership. Grasso entered the Senate as a Democrat in 2013, but quit the party in October.

The opposition populist 5-Star Movement is hoping to win its first premiership in a general election due next spring. Ex-Premier Silvio Berlusconi hopes his own center-right Forza Italy party will make a comeback and regain national power.