Poland's conservative President Karol Nawrocki on Friday vetoed a bill to legalise civil partnerships, he announced in a statement.
The legislation had been proposed by Prime Minister Donald Tusk's centrist government ahead of last year's parliamentary elections in Poland.
"I have always emphasised that nothing that is a quasi-marriage can count on my support," Nawrocki said on X.
"As the guardian of the Constitution, I cannot accept a solution that would lead to the loss of the special status of marriage defined... as a union of a woman and a man."
The bill, first submitted to parliament last December, aimed to establish a "status of the closest person" for unmarried partners, including same-sex couples.
The unions would grant some of the rights currently reserved for married couples under Polish law, such as joint property rights, access to each other's medical information and burial rights.
To ease conservative opposition, leaders of the ruling coalition have stressed that "closest person" unions would not have to be between romantic partners, but could also be formed by neighbours or family members.
Following the president's veto, Tusk criticised it on X as "an expression of contempt toward people and their right to happiness and a normal life".
Last year, Tusk's pro-European Civic Coalition pledged to introduce a bill to legalise civil partnerships within its first 100 days in office.
However, governing with more conservative coalition partners and sharing power with Nawrocki has meant that many of the party's campaign promises on social issues have taken longer to reach a compromise and come to a vote.
In 2025, state research agency CBOS found that 62% of Poles supported legalising same-sex partnerships - the highest level of support ever recorded for the measure.
Poland, alongside Bulgaria, Romania and Slovakia, is one of the last countries in Europe not to have legalised same-sex marriage or civil unions
