Reuters / Giorgio Perottino
Comedian and Five Star Movement co-founder Beppe Grillo
Italy's Five Star Movement (M5S) was back in the headlines on Sunday for its major role in a bitter - and successful - campaign against prime minister Matteo Renzi's proposed constitutional reforms. The No vote it backed in the referendum forced Renzi's resignation.
Polls indicate M5S is now the most popular opposition party in Italy, and it looks well-placed to make a bid for power if a snap election is called. But what exactly is this insurgent movement, and where has it come from?
Online beginnings
Founded in 2009 by comedian Beppe Grillo and web strategist Gianroberto Casaleggio, the party was based on "the twin ideas of a new form of direct democracy and popular disgust with the political elites," according to
The pair felt that a new party could harness the power of the internet to create a new type of movement - and they were right. Grillo - an admirer of UKIP's Nigel Farage - used his personal website and social media channels to promote meetings and encourage followers to stand as candidates in local elections, and the party's populist message attracted voters from traditional parties across the country.
Populist policies
The party's policies don't fit neatly into the traditional left-right political spectrum, something the party is keen to emphasise. It is variously anti-establishment, Eurosceptic, anti-immigration and pro-green. The "Five Stars" refers to its five flagship issues: publicly owned water, sustainable (eco-friendly) transport, sustainable development, right to internet access, and environmentalism.
However mixed its messages might seem, they worked. Voters, disillusioned with the "status quo" and politicians' weak response to the economic downturn, began to lodge their protest by supporting M5S at the ballot box. In Italy's 2013 general election, the party picked up 30% of the vote (although it won only 106 of over 600 seats due to a voting system which favours parties in coalition). In terms of vote share, they were the second-most popular party, and support has remained on a similar level ever since.
Pro-"Itexit" referendum on the EU
Professor James Newall believes that the party's eclectic mix of policies is both a strength and a weakness. It can appeal to many kinds of voters, and picks up the "protest" votes of many who define themselves in opposition to whichever mainstream party is ruling - but its supporters often disagree on key issues. On major policy points like EU membership, taxation, or migration, Newall says "M5S voters are more or less split down the middle."
Grillo's position on EU membership is clear enough, however: he would call a referendum, and hopes it would herald Italy's own Brexit ("Itexit").
Problems in power
Experience of power hasn't gone well so far. Eighteen of its 106 elected MPs have defected from the party since 2013. M5S candidate Virginia Raggi was elected as Mayor of Rome - a hugely influential position - in June this year, and it has been chaotic. She has been rocked by the resignations of four top officials, by a scandal over the appointment of a public sanitation chief, and by accusations that she is a pawn of party leader Grillo.
To some, Raggi's disastrous reign is clear evidence that the party is one of protest, not government.
What next?
M5S got its wish on Sunday when Renzi announced his resignation, and Grillo has already called for a snap election. An EMG survey released on Sunday indicated that M5S would win in a two-round voting system, under new electoral reforms pushed through this year by Renzi.
There's no guarantee that an election will be called. Renzi will hand in his resignation to President Sergio Mattarella on Monday afternoon, and his referendum defeat was so big that he may be forced out as leader of the Democratic Party, which has the most seats in parliament. There are a few frontrunners within the party to succeed Renzi, but it remains to be seen whether Mattarella can oversee a smooth transition, or if he has to call an election.
If he does, the man billed by some as "Italy's Trump" could soon be running one of Europe's largest economies, with potentially huge ramifications for the future of the Eurozone.