Sluggish economy
Analysts said a strong lead in both houses of parliament would allow for Berlusconi more flexibility to carry out economic and social reforms he promised.
Once in office for the third time, Berlusconi will face the imminent task of saving a sluggish economy from recession, a major concern weighing heavily on most voters.
The Italian economic growth has been under potential in recent years. In 2007, it was 1.5 percent, far below the eurozone average of 2.7 percent.
The 2.4-trillion-U.S. dollar economy, the fourth largest in the European Union (EU), was projected to grow merely 0.3 percent this year, according to a forecast by the International Monetary Fund earlier this month, the slowest among the more than two dozen "advanced economies."
With a government debt of 1,400 billion euros (2,200 billion U.S. dollars), more than its annual gross domestic product, Italy is Europe's most-indebted country, incurring a per capita annual debt interest of some 1,200 euros (1,900 dollars).
Berlusconi had promised to lower taxes and cut public spending. His People of Freedom party planned a reduction in payroll taxes and contributions to help make businesses more competitive. It also pledged to introduce measures to protect and bolster Italian exports.
But many Italian voters wanted to see concrete results rather than repeated pledges, criticizing him of inaction on his promises during his second term as prime minister from 2001 to 2006.