ROME — Will Italy stay the course with painful economic reform? Or fall back into the old habit of profligacy and inertia? These are, broadly, the choices 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.