Republican Ken Buck is now walking back a comment he made after a campaign stop last month aimed at those who question President Obama’s citizenship.

The audio of Buck, which was captured by a Democratic Party tracker, surfaced over the weekend. He said: “Will you tell those dumbasses at the Tea Party to stop asking questions about birth certificates while I’m on the camera.”

The candidate said Monday he regrets using the word, noting that he has been frustrated that questions over the president’s birth certificate have overshadowed larger issues. 

Buck’s Republican primary opponent Jane Norton quickly seized on the comments. Her campaign put out a statement calling Buck “a self-proclaimed tea partier who trashes tea partiers when he thinks no one is looking.”

And Norton is planning a news conference for Monday afternoon to “address Buck’s Tea Party betrayal.”