Civic Platform (PO) legislators have been occupying parliament since mid-December after the governing Law and Justice (PiS) party announced plans to restrict journalists' right to cover legislative proceedings, a position from which the PiS has since retreated.
The opposition then harnessed the protest to this year's budget vote.
It wants a re-run of the vote which it says was illegal as the governing party passed it in December in another part of the building because the opposition had taken over the main chamber.
PO leader Grzegorz Schetyna today called for parliament to be adjourned until January 18 in a bid to buy time to find a way out of the stalemate.
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PiS parliamentary caucus chief Ryszard Terlecki agreed, but on the condition that opposition lawmakers would first end the sit-in.
"In reality, this isn't any kind of new proposal," Schetyna said. "They want us to quit the parliamentary chamber but they're not offering us anything in return."
Powerful PiS party leader Jaroslaw Kaczynski has slammed the sit-in as "an attempted coup".
Poland has been mired in political crisis for months.
In December, the EU gave the PiS government another two months to reverse changes it made to Poland's constitutional court or face sanctions, warning they posed a "substantial" challenge to the rule of law.
This and the crisis in parliament come just over one year after the conservative PiS swept to power and began pushing through legislation that critics allege undermines democracy.
Although the moves have sparked mass anti-government street protests, the PiS remains widely supported and has kept well ahead in recent opinion polls due in large part to its generous social spending schemes.