Analysis - Italy's Grillo facing showdown as 5-Star mutiny swells

Leader of the anti-establishment 5-Star Movement Beppe Grillo gestures during a news conference in Rome April 21, 2013. REUTERS/Remo Casilli

ROME (Reuters) - Beppe Grillo, the fiery comic whose populist 5-Star Movement stunned Italy by winning a quarter of the votes in February's election, is facing his biggest test since the vote with rebellion brewing among his novice lawmakers.

Publicly blamed by one of his own senators for the party's poor showing in local elections earlier this week, in which it won only two towns out of more than 500, Grillo faces the threat of a mutiny that could blow the party apart.