Silvio Berlusconi, Italy's flamboyant prime minister, is usually reluctant to admit defeat. But once it became clear that the majority of Italian citizens defied his exhortations not to vote and weighed in on four national referendums, he waxed philosophical: “In respect to the people's will, we shall say goodbye to nuclear energy,” he told news agencies. “This means we'll have to put more effort on renewable [energy sources].”

But many observers see the beginning of the end for Mr. Berlusconi in both the large turnout and voters' rejection of trial immunity for government ministers – a measure introduced last year that granted Berlusconi de-facto immunity from prosecution. The embattled leader is currently facing three corruption trials and one for allegedly having sex with an underage prostitute.

“The countdown for Berlusconi has begun,” argues Paolo Franchi, a political analyst for Il Corriere della Sera, Italy's major newspaper. “Only 20 days ago I wouldn't have said so, but it seems now clear that this government is in a severe crisis,” adds Mr. Franchi.

In late May, Berlusconi's right-wing coalition suffered a major blow in a round of local elections, when progressive candidates were elected mayors in all the large cities involved. In addition to Naples and Turin, the defeat was particularly harsh in historically conservative Milan, the prime minister's hometown, where Berlusconi had symbolically run himself for the city council.

“If we read the local elections and the referendum results together, this clearly tells us that Berlusconi is losing appeal also among conservative voters,” says Franchi.

In addition to their refusal to support Berlusconi's immunity, voters rejected a law that had allowed the reintroduction of nuclear energy in 2009, after a 20-year ban. The two other ballot questions involved the privatization of water resources, which voters also turned down.

When polls closed, about 57 percent of voters had participated the referendum, surpassing the required quorum of 50 percent plus one. Official results will be declared later tonight, or in the early morning. But according to Instant Poll EMG polling agency, all four national referendums were approved with more than 91 percent of the votes.

“Even in the unlikely hypothesis that all progressive voters had gone to the polls," points out Franchi, "this means that a significant number of conservative citizens voted against Berlusconi, in spite of his vocal campaign against the referendum.”

The conservative government faces a further challenge on June 22, when, at the request of President Giorgio Napolitano, the recently reshuffled coalition will undergo a confidence vote in the Parliament. “Given the political climate, I wouldn't be surprised if the Parliament will pass a no-confidence vote,” says the analyst. He argues that early elections are unlikely before the summer recess, but that after that, a “big change” is to take place.