ROME — The European debt crisis appeared to claim its most prominent victim on Tuesday when Prime Minister Silvio Berlusconi of Italy, cornered by world markets and humiliated by a parliamentary setback, pledged to resign after Italy’s Parliament passes austerity measures demanded by the European Union.

Although Mr. Berlusconi’s exit was not immediate — weeks of political wrangling over the austerity measures probably lie ahead — political commentators said they could see no escape this time for the prime minister, whose Houdini-like ability to wriggle free from scandals is legendary.

“A season is over,” said Mario Calabresi, the editor in chief of the Turin daily newspaper La Stampa, who said Mr. Berlusconi told him that he was not only stepping down, but also would not run for office again.

In the end, it was not the sex scandals, the corruption trials against him or even a loss of popular consensus that appeared to end Mr. Berlusconi’s 17 years as a dominant figure in Italian political life. It was, instead, the pressure of the markets — which drove Italy’s borrowing costs to record highs this week — and the European Union, which could not risk his dragging down the euro and with it the world economy.