ROME (Reuters) - The leader of Italy’s 5-Star Movement, Luigi Di Maio, said on Wednesday he would seek a confidence vote from party supporters after a bruising defeat in European elections.

Italian Deputy Prime Minister and 5-Star Movement leader Luigi Di Maio casts his vote in the European election in Pomigliano d'Arco, Italy May 26, 2019. REUTERS/Ciro de Luca

The ballot will take place online on Thursday on a dedicated platform linked to the party, Di Maio -- who is deputy prime minister in a coalition government with the right-wing League -- said in a post on 5-Star’s blog.

“Today, I have the right to know what you think of my actions. I want to hear the voice of the citizens who elected me as political leader a few years back,” Di Maio said.

The League, led by Interior Minister Matteo Salvini, won 34.3% of the vote in Sunday’s election, doubling the score of the anti-establishment 5-Star Movement, which took just 17.1% and was pushed into third place by the center left.

That almost exactly inverted the result of national elections a year ago that led to the coalition between the two.

Since Sunday’s vote, Salvini has been behaving as if he were already prime minister, promising swinging tax cuts and calling for a European Union meeting to change the bloc’s budget rules, while Di Maio has come under attack from within 5-Star.

Prominent 5-Star senator Gianluigi Paragone said on Wednesday that Di Maio had too much power in the party and too many roles in government.

“If you want to act like a Superman, you have to demonstrate you really are one,” he told newspaper Corriere della Sera.

As well as being 5-Star leader and deputy prime minister, thirty-two year-old Di Maio serves as industry minister and labor minister in the government formed last June.

5-Star’s ministers and parliamentarians will meet on Wednesday evening to discuss the election debacle and how best to counter Salvini, who is also deputy prime minister and is now seeking to drive the policy agenda.

If 5-Star bows to the League’s demands it risks losing more support among its core voters. If it does not, that might trigger a government collapse and fresh elections which would be likely to reward Salvini.

“I haven’t stopped working for the last 6 years and I think I have always honored my duties, always making myself accountable to all the movement’s members and activists,” Di Maio said.

When he was elected party leader in September 2017, Di Maio was widely dismissed as a puppet for the movement’s founder, comedian Beppe Grillo, but he rapidly consolidated his power while Grillo has disappeared from the limelight.

In the March 2018 election, 5-Star won almost twice as many votes as any other party, but Di Maio’s claim to be named prime minister was vetoed by Salvini when the two parties joined forces in government.

Their compromise choice of premier, Giuseppe Conte, is a former academic who is close to 5-Star but is not a member of either party.