Luigi Di Maio stepped down on Wednesday as leader of Italy's co-ruling 5-Star Movement, in a move that underlines the deep divisions in the party and adds to uncertainty for the fractious governing coalition. 

"Today I am here to tender my resignation as head of the 5-Star Movement," Di Maio told party members at an event to present a new structure of regional chiefs. 

He said Vito Crimi, the head of 5-Star's internal rules committee, would take over as caretaker until a new leader is chosen following a party congress to be held in the coming months.

In response, Italian Prime Minister Giuseppe Conte said he would respect any decision his foreign minister made. "I am sure he would take such an initiative with great responsibility," Conte told Italian radio RTL 102.5, declining to comment further.

The 5-Star won 33 percent of the vote in a national election in 2018, but since then its popularity has fallen sharply and recent polls put it at around 15 percent.

It initially formed a coalition with the far-right League, switching to an alliance with the left-wing Democratic Party (PD) last September after League leader Matteo Salvini walked out of government.

Di Maio was sceptical about joining the PD in government but, with many of the party's lawmakers opposed to fresh elections, was reluctantly persuaded to sign up by 5-Star founder Beppe Grillo.

Tensions within the party have been fueled further by a perception that Di Maio has failed to share power outside his inner circle of advisers.

Since the election, more than 30 lower house and senate lawmakers have left 5-Star's parliamentary grouping, some defecting and some being ejected.

That exodus has left the government with only a wafer-thin majority in the upper house Senate.

(With input from Reuters, Xinhua)

(Cover: 5-Star Movement leader Luigi Di Maio after consultations with Italian President Sergio Mattarella in Rome, Italy, August 22, 2019. /Reuters Photo)