Mr. Salvini’s critics see a more straightforward case of his breaking the law, not to mention disregarding the dire human suffering of those on board the ships he left floating at sea, and of a judicial system doing its job to hold him accountable. They are doubtful that Mr. Salvini will actually vote for the case to go ahead in another legislative step on Feb. 12. His office says it is still evaluating what to do.

Either way, Mr. Salvini, despite his complaint about having to eat breakfast with his lawyer rather than his girlfriend, is now relishing the opportunity.

In the politics of persecution, Mr. Salvini has few peers, having picked up where Silvio Berlusconi left off. The media magnate and former conservative prime minister spent decades excoriating Italy’s prosecutors as the country’s Communist opposition — to great political fortune.

Mr. Salvini has replaced Mr. Berlusconi as the de facto leader of the Italian right, though he has sat on the sidelines since his coalition government collapsed last summer.

Before then, in one of his last official acts, Mr. Salvini prevented the Italian Coast Guard ship, the Gregoretti, from bringing rescued migrants to an Italian port for days.

On Dec. 17, a court in the southern city of Catania asked a panel in the Italian Senate to lift Mr. Salvini’s immunity and allow him to be prosecuted for “abducting” the migrants by refusing to let the Gregoretti dock.

On Jan. 31, a Palermo court made a similar request concerning a Spanish aid boat carrying scores of migrants, some of whom Mr. Salvini kept adrift for weeks, in violation of a court order allowing them to enter Italian waters.