Robert Biedron, an openly gay politician, will challenge the current president in the upcoming May Polish election.

Three liberal parties tapped Biedron to run against the conservative President Andrzej Duda and another liberal candidate, NBC News reported. Biedron, 44, has been an activist in Poland, has served as a Parliament member, and was the mayor of Slupsk, Poland. The president’s party has been active against LGBT rights in the past, something Biedron is working to alleviate.

“The left proves once again that cooperation works well for us. And we will continue to do so — for the good of Polish women and men,” Biedron wrote on Twitter.

Biedron is also active for women’s rights, climate change and democracy, NBC News reported.