The lower house of the Polish parliament approved the European Union's new treaty on Tuesday (1 April).
The document, which EU leaders signed in December in Lisbon and which aims to revitalise the bloc's institutions and boost its efficiency, was approved by 384 deputies from the 460-seat lower house, the Sejm.
Fifty-six parliamentarians out of the 452 present voted against the bill, which enables the president to officially ratify the treaty, while 12 abstained - all of them hardliners within the conservative Law and Justice Party.
The Sejm's special session was convened after Liberal Prime Minister Donald Tusk (Civic Platform party) and conservative opposition leader Jaroslaw Kaczynski of the Law and Justice Party struck a deal on Tuesday (31 March), lifting the threat of a block by the opposition.
Mr Kaczynski had been threatening since mid-March to obstruct ratification of the Lisbon treaty unless Warsaw won more guarantees on sovereignty, and on the Polish constitution remaining the highest law in the country.
Supported by his twin brother, Polish President Lech Kaczynski, the former premier had evoked anti-German and homophobic arguments, fearing for instance that gay marriages could be "imposed" on Poland, should the Lisbon treaty be ratified in its current form.
His party voted in favour of the treaty on Tuesday, however, after reaching an agreement with Prime Minister Tusk to have a parliamentary resolution adopted that would contain references to Poland's sovereignty in the face of EU legislation.
Poland's President, present at the session, also told parliamentarians that the adoption of the treaty would be good news for both Poland and the EU, according to German news agency DPA.
The ratification bill is now expected to be approved by the Polish Senate on Wednesday (2 April). The process will then be finalised with a signature by the country's president.
So far, Poland, Hungary, Slovenia, Malta, Romania, France and Bulgaria have approved the document.
Ratification of the Lisbon treaty is expected to be finalised by the end of this year, in order that the treaty can come into force in 2009.
So far, only Ireland is to hold a referendum on the treaty, expected in June.