The 32-year-old actress said on Wednesday's episode of "Watch What Happens Live" that she was proud of Swift for endorsing Democrats this week ahead of the midterm elections.
"That was really amazing," Dunham told host Andy Cohen.
"I mean, I'm always proud of Taylor. Not only is she an amazing friend to me on a personal level, but she's an amazing friend to lots of people in the world."
"She felt it was time for her to talk about politics. I never judged her for considering that a private domain, but I think she chose a really, really powerful time to speak out," she said.
"I'm so moved and honored to be her friend."
Swift spoke out in an Instagram post Sunday after keeping her political beliefs private for years.
She said she would be voting for Democratic candidates Phil Breseden and Jim Cooper for the Senate and House of Representatives, respectively.
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"In the past I've been reluctant to publicly voice my political opinions, but due to several events in my life and in the world in the past two years, I feel very differently about that now," the 28-year-old singer explained.
"I always have and always will cast my vote based on which candidate will protect and fight for the human rights I believe we all deserve in this country," she said.
"I cannot vote for someone who will not be willing to fight for dignity for ALL Americans, no matter their skin color, gender or who they love."
Dunham is a longtime friend of Swift's who appeared in the singer's "Bad Blood" music video.
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