By Gavin Jones
ROME (Reuters) - An online vote on Friday by members of the anti-establishment 5-Star Movement could strengthen its new government with the centre-left Democratic Party (PD) and sow the seeds of a new bipolar structure in Italian politics.
5-Star's members were choosing whether to field a joint candidate with the PD in an election next month to pick a new governor of the central region of Umbria.
A vote in favour would mark a reversal of 5-Star's traditional rejection of election pacts and the repercussions will extend far beyond Umbria, a land-locked region of 900,000 inhabitants.
By joining forces in Umbria, traditionally a PD stronghold, 5-Star and the PD would hope to halt a long streak of victories by the centre-right, which has triumphed in seven regional ballots since a national election in March 2018.
Success at the Oct. 27 Umbria vote would probably pave the way for similar alliances in the next few months in the regions of Emilia-Romagna in the industrial north and Calabria in the poor south.
In the medium term, analysts say this would create the conditions for 5-Star and the PD to become a stable alliance that would contest future local and national elections against a conservative bloc led by Matteo Salvini's hard-right League.
5-Star governed Italy with the League until last month, when Salvini pulled the plug on the coalition in a vain attempt to trigger elections he expected to win. Instead, 5-Star formed a new government with the PD, pushing Salvini into opposition.
ENMITY AT LOCAL LEVEL
However, the path to stable 5-Star/PD cooperation may not be smooth.
Driven by a common desire to block Salvini, the traditional adversaries overcame their differences to form a national government, but fielding joint candidates in regional and mayoral elections requires a deeper level of cooperation.
Mutual enmity still runs deep among activists at local level, and some of 5-Star's most prominent figures have publicly rebelled against the coalition with the PD, fomenting internal party tensions.
On Thursday Alessandro Di Battista, considered a potential future 5-Star leader, warned his colleagues not to trust the PD, calling it Italy's most pro-establishment and "dangerous" party and "the most hypocritical party in Europe."
Even if 5-Star's members vote to join forces with the PD in Umbria, the two parties still need to find a mutually acceptable candidate for governor. Preliminary talks have made little progress, running up against vetoes and local rivalries.
5-Star's pre-condition for any local deals is that candidates must come from so-called "civil society", meaning they are not career politicians or members of either party.
The online vote on 5-Star's purpose-built platform, known as Rousseau, began at 0800 GMT. The result is expected to be announced shortly after 1700 GMT.
(Reporting by Gavin Jones; Editing by Andrew Cawthorne)