Former Italian Premier Matteo Renzi resigned on Sunday as leader of his fractious Democratic Party in a bid to win a fresh, stronger mandate before parliamentary elections which populist political forces hope will propel them into national power for the first time.

As promised a week earlier, Renzi told fellow Democratic leaders he was resigning in view of an eventual party congress to decide electoral platforms and the next leader. No one immediately challenged him for a new mandate as party secretary.

But Renzi insisted he wouldn't submit to a more left-leaning faction threatening schism if he again sought the top party post.

The only word uglier than schism, he said in a speech at an assembly at a Rome hotel, "is blackmail, a diktat from the minority."

Some in the faction had openly defied Renzi by urging voters to reject a government-sponsored referendum on constitutional reforms, aimed at making Italy more governable. The referendum went down to defeat on Dec. 4, prompting Renzi's resignation as premier after nearly three years in the post.

Election for Parliament, due in early 2018, might come earlier if Premier Paolo Gentiloni, who was tapped to replace Renzi, loses control of the frequently squabbling center-left parliamentary majority.

The populist, anti-euro 5-Star Movement, led by a satirical comic Beppe Grillo, aims to govern Italy for the first time, after winning several mayors' posts, including last year in Rome.

With Italy's economy failing to rebound for years, opinion polls show the 5-Stars fast gaining ground. Right-wing forces, including the anti-immigrant Northern League and a smaller party with neo-fascist roots, hope to ally with the 5-Star Movement in a government.

Renzi and other top Democrats urged the party to worry about populism rising in Europe and concentrate on what matters to voters, like high unemployment. Otherwise, he said, "they'll take us for crazy" if squabbling continues.