At a campaign stop in Iowa, presidential hopeful Pete Buttigieg, the openly gay mayor of South Bend, Indiana, accused President Donald Trump of paying “lip service” to LGBT rights.

The accusation comes after the president said in a Fox News interview that he was “absolutely fine” with Buttigieg's sexuality and thought it a sign of progress that he appears at campaign events with his husband Chasten.

“Even though they're paying lip service to the idea of – like the president was asked about my marriage, so he could have the opportunity to say he's fine with it,” Buttigieg is quoted as saying by ABC News. “That's fine.”

Trump told Fox News: “I think it's absolutely fine. I do. I think it's great. I think that's something that perhaps some people will have a problem with. I have no problem with it whatsoever.”

(Related: Trump says “some people” might have a problem with Pete Buttigieg's sexuality.)

Referring to reports that the Trump administration refused to issue the equivalent of a U.S. birth certificate to a baby born in Canada via surrogate to a married same-sex couple who were biologically related their child, Buttigieg called the change in policy “discrimination.”

“We find out this week that they changed the State Department guidance,” Buttigieg told the crowd. “So if you are, for example, in an international adoption scenario, and you're a same-sex couple, as far as the United States government is concerned, you have a child born out of wedlock. Think about what that means. It means you are not a citizen of the same country as your own child at the time that they are born. And that's discrimination.”

During a radio appearance on Friday, Buttigieg was asked about his criticism of Vice President Mike Pence, who has said his faith informs him to oppose marriage for gay and lesbian couples.

Pence “advances homophobic policies,” Buttigieg told conservative radio host Hugh Hewitt.

(Related: Pete Buttigieg: Mike Pence shouldn't use religion to justify harming LGBT community.)