By Crispian Balmer
ROME (Reuters) - Members of Italy's ruling governing party the 5-Star Movement voted on Monday to block a possible kidnapping trial against Matteo Salvini, its coalition ally and leader of the hard-right League party.
The online ballot is meant to dictate how 5-Star senators should vote on Tuesday in a parliamentary committee reviewing whether magistrates can continue a probe into Salvini, who is also interior minister and deputy prime minister.
5-Star said on its website that 59 percent of its members had voted to protect Salvini - a result that will help defuse tensions within the government.
The contested case has sown division within 5-Star, which has built its support on pledges to bring transparency to Italian politics and has traditionally denounced parliamentary manoeuvring to halt judicial proceedings against lawmakers.
Prosecutors in Catania, Sicily, need permission to continue an investigation for alleged abuse of power and kidnapping that began when Salvini ordered some 150 migrants be held onboard an Italian coast guard ship for five days in August.
Salvini has asked for parliamentary immunity, saying the case focuses on decisions taken by the entire government for the good of the country.
Some of his supporters have questioned how he could stay in an alliance with 5-Star if it did not rally to his side.
Looking to deflect any blame over the awkward decision, 5-Star leader Luigi Di Maio decided to turn the question over to the party's membership. Some 52,000 party supporters cast a ballot despite technical issues on the website.
After the Senate's Elections and Immunity Commission rules on the matter, the issue must go before the full Senate for ratification. While some 5-Star lawmakers have indicated they want to see the legal probe continue, the online vote is likely to tie their hands.
Tensions within the coalition are running high, with the allies at odds over a long list of issues, including whether to forge ahead with a new Alpine rail tunnel between France and Italy and whether to grant Italy's regions more autonomy.
The 5-Star blog post announcing the online vote said the decision to block the migrants on board the Diciotti coast guard vessel was not Salvini's alone, but was shared by Di Maio and Prime Minister Giuseppe Conte.
Since forging a coalition with the League last June, support for 5-Star has fallen sharply, while backing for Salvini has soared, complicating relations between the two parties.
The League has doubled its support to around 34 percent in just a year, lifted by Salvini's anti-immigration stance. By contrast, 5-Star has dropped to some 24 percent - down about 8 percentage points since national elections last March.
(Reporting by Crispian Balmer; Editing by Peter Cooney)