Inside Parliament, tensions ran high. At one point, fisticuffs broke out, and lawmakers accused one another of assault, releasing contradictory videos accusing rivals of starting the fight. Meanwhile, supporters brought in food, including a small traditional Polish feast on Christmas Eve.

The opposition at times found it difficult to maintain a united front. On New Year’s Eve, Ryszard Petru, the leader of Modern, another opposition party involved in the sit-in, was photographed with a female lawmaker aboard a plane that was reportedly going to the Portuguese island of Madeira — after he had stated that opposition lawmakers should refrain from vacationing during the holidays. Amid the uproar, he apologized for what he acknowledged was an “indiscretion,” though he denied that he had been flying to Madeira. (He refused to say where he was headed.)

The standoff only underscored concerns that European Union officials have raised about the state of democracy in Poland, where the government has moved to curb the independence of the judiciary and the news media.

On Thursday, Grzegorz Schetyna, the head of Civic Platform, said that after “succeeding at securing media’s access to the parliament building, as well as their unrestricted right to cover the parliamentary proceedings, we are suspending our protest.”

However, the issue of the budget — and whether it was lawfully passed — has not been resolved.

“We still consider the budget legislation to be illegal, and we appeal to President Andrzej Duda not to sign it,” Mr. Schetyna told reporters on Thursday.