A petition against the appointment of Mr. Bernatowicz was signed by Olga Tokarczuk, the Polish novelist who was awarded the delayed 2018 Nobel Prize in Literature, along with a Who’s Who of the Polish art world. He would “go down in history as the gravedigger of this institution,” wrote a commentator in Krytyka Polityczna, a highbrow left-wing magazine.

Mr. Bernatowicz said he was aware of the criticism, but was undaunted. “Why shouldn’t I try?” he said.

The Law and Justice Party has tried to orientate Poland’s cultural institutions in a nationalist-populist direction since it was elected in 2015. Piotr Glinski, Poland’s culture minister, who appointed Mr. Bernatowicz at the Ujazdowski, said in an emailed statement that the government was “restoring the right balance and building a fair system, in which every artist, regardless of his/her views, can count on the support of the state.”

Other government-appointed art administrators have caused controversy, too. In April, Jerzy Miziolek, the director of the National Museum in Warsaw, removed three contemporary artworks, all by women, from its walls after he received an email from a visitor who said her child had been left traumatized by them.

The works included a photo series by Natalia L.L., a feminist artist whose career began in Poland under Communism, that showed a woman seductively licking and sucking a banana. Demonstrators ate bananas outside the museum in protest at its removal. (Mr. Miziolek resigned in December after a series of labor disputes at the museum.)