By Colleen Barry and Victor L. SimpsonROME -- Will Italy stay the course with painful economic reform? Or fall back into the old habit of profligacy and inertia? These are the stakes as Italians vote in a watershed parliamentary election Sunday and Monday that could shape the future of one of Europe's biggest economies. Fellow European Union countries and investors are watching closely, as the decisions that Italy makes over the next several months promise to have a profound impact on whether Europe can decisively put out the flames of its financial crisis. Greece's troubles in recent years were enough to spark a series of market panics. With an economy almost 10 times the size of Greece's, Italy is simply too big a country for Europe, and the world, to see fail. Leading the electoral pack is Pier Luigi Bersani, a former communist who has shown a pragmatic streak in supporting tough economic reforms spearheaded by incumbent Mario Monti. On Bersani's heels is Silvio Berlusconi, the billionaire media mogul seeking an unlikely political comeback after being forced from the premiership by Italy's debt crisis. Monti, while widely credited with saving Italy from financial ruin, is trailing badly as he pays the price for the suffering caused by austerity measures. Then there's the wild card: comic-turned-politician Beppe Grillo, whose protest movement against the entrenched political class has been drawing tens of thousands to rallies in piazzas across Italy. If his self-styled political "tsunami" sweeps into Parliament with a big chunk of seats, Italy could be in store for a prolonged period of political confusion that would spook the markets. Voting was generally calm. But when Berlusconi showed up at a Milan polling place to cast his ballot, three women, shouting "Enough of Berlusconi," pulled off their sweaters to bare their chests, and display the slogan "Basta Silvio!" (Enough of Silvio) scrawled on their flesh. A cordon of police, already in place for security before the former premier's arrival, blocked Berlusconi's direct view of the topless women. Police detained the women for questioning. Italian news reports said the three were members of the Femen protest group.