“In the beginning, MPs were targeted with threatening messages. Then with posters. Then came the assault squads at Parliament. And now we have arson attacks on MPs’ homes,” Mr. Tsipras wrote on Twitter. Politicians who do not condemn violence, he added, “bear a huge responsibility.”

Despite the upheaval, Mr. Tsipras is all but certain to gain approval for the Macedonia pact with the support of a few opposition and independent legislators. Some of his support is expected to come from lawmakers who have broken ranks with Panos Kammenos, the leader of a junior coalition partner, the Independent Greeks, who quit as defense minister this month in protest of the Macedonia deal.

Mr. Kammenos’s withdrawal prompted Mr. Tsipras to call a confidence vote, which he won.

Mr. Tsipras has insisted that his government would remain in power until October, when its four-year term is set to end. Analysts believe, however, that he is likely to call elections earlier, possibly in May.

So many lawmakers asked to speak on the deal that Parliament postponed the vote, which had been expected to take place after midnight on Friday, to midafternoon.

One of the lawmakers’ main contentions is that debate on the deal is “inconceivable” without a revised version of Macedonia’s Constitution, reflecting the changes agreed to by the two sides.

The version of the Constitution presented to the Greek Parliament has those changes listed at the end, but Deputy Foreign Minister George Katrougalos insisted on Wednesday that they would be enshrined in the body of the Constitution after the deal’s ratification by Greece.

Macedonian lawmakers approved the name change this month, contingent on Greek approval.

A conservative former prime minister, Kostas Karamanlis, who was in power when Greece blocked Macedonia’s NATO bid in 2008, said in a written statement that the deal was sealed “in undue haste,” adding that the government “should have respected the sensitivities and listened to the legitimate concerns of the large majority of citizens.”