Rome, June 18 - Dozens of demonstrators loyal to Beppe Grillo, the founder and leader of the troubled 5-Star Movement (M5S), staged a protest outside the Italian Lower House Tuesday amid a widening rift over a Senator who may be kicked out of the anti-establishment party. "Beppe is the megaphone, we're the voice of the movement," read a banner. Several M5S MPs also took part in the demonstration. It was launched in response to growing criticism by so-called "dissidents" in the group, the most vocal of whom has been Senator Adele Gambaro. Last week she called Grillo "a problem for the movement" after the party's flop at local elections across the country, when the center-left Democratic Party (PD) swept all provincial capitals up for grabs, including Rome. Pundits cited the M5S's unwavering refusal to compromise with the PD since February's inconclusive general elections as a sign of M5S disaffection and low voter turnout at the last vote. Late Monday 5-Star MPs voted in favor of kicking Gambaro out of the party, but opted to give the rank and file the final word in an online poll. The affair is viewed as a defining moment in the movement founded online in 2009 by the Grillo, a comedian known for irreverent rabble-rousing. While a majority of M5S MPs present, 79, voted to oust Gambaro, a significant minority of 42 voted against it, with nine abstaining. Those "dissidents" are believed to be on the verge of defecting to the PD, which was forced to ally with the center-right People of Freedom (PdL) party of three-time premier Silvio Berlusconi in April in order to break a two-month parliamentary gridlock and give the country a government.