Silvio Berlusconi was heading on Mondayfor a second defeat in less than two weeks as his government admitted its opponents had succeeded in getting more than 50% of the electorate to vote in popular referendums including one on nuclear power.

The outcome of the four ballots, which will be known later on Monday, looked certain to dash the plans of Italy's embattled rightwing government for a big nuclear construction programme and water privatisation.

Berlusconi said: "We shall have to say good-bye to nuclear [energy]." He told a press conference in Rome that his government would now throw all its energy into developing renewable sources.

The expected outcome would be a huge success for the anti-nuclear movement in the world's first nationwide vote on the issue since Japan's Fukushima disaster. But the ballot was also the latest - and most persuasive - evidence that a majority of Italians has turned against their flamboyant prime minister.

Under Italian law, referendums require more than half the electorate to vote to be binding. The government did all it could to keep turnout low and appealed to the courts for the vote to be declared illegal. Italian television, largely under Berlusconi's sway, almost ignored the approaching ballots until the final days of a poorly funded, low-profile campaign.

Yet the interior minister, Roberto Maroni, said his department's projections indicated the opposition would reach its 50% target, regardless of the turnout among more than three million Italians overseas who are entitled to vote.

Berlusconi's government, which yokes his Freedom People movement to the regionalist and Islamophobic Northern League, first ran into serious trouble on 30 May when his candidate for mayor of Milan lost in a local election runoff. Milan is Berlusconi's home city and has traditionally been a weather-vane, accurately pointing to Italy's future political direction.

Since then, many rank-and-file league supporters have been urging their leader, Umberto Bossi, to cut himself free of Berlusconi. The party leadership has so far remained wedded to the coalition while pressing for a radical change in economic policy that would deliver tax cuts to its lower middle-class electoral base.

Italy abandoned its nuclear programme following a similar referendum in 1987. But the moratorium it introduced only remained in force for five years. Berlusconi had planned to generate a quarter of Italy's electricity with French-built nuclear plants.