ROME  Prime Minister Silvio Berlusconi’s fiercest rival withdrew four loyalists from the cabinet on Monday, deepening a political crisis that is expected to bring down the government in a matter of weeks and very likely lead to early elections.

Tensions have been rising since July, when Gianfranco Fini, the co-founder with Mr. Berlusconi of the center-right People of Liberty party, split with the prime minister, accusing him of running an antidemocratic party. Mr. Berlusconi then expelled him from the ruling coalition, a move that cost Mr. Berlusconi his parliamentary majority.

Those tensions boiled over this month, when Mr. Fini, the speaker of the lower house and a former neo-Fascist now seen as a moderate, made it clear that the situation was beyond repair. At a meeting of his breakaway parliamentary group, Future and Liberty, he vowed to withdraw his ministers if Mr. Berlusconi did not resign.

Mr. Berlusconi refused, and on Monday, Mr. Fini withdrew one minister, one deputy minister and two under secretaries from the cabinet. This further weakened the government, which is expected to fall in a confidence vote.