A television ad in Wyoming attacks Liz Cheney for her supposed support for gay marriage.

Cheney, the daughter of former vice president Dick Cheney, is challenging Wyoming Senator Mike Enzi in the upcoming Republican primary.

After a male announcer describes cabler MSNBC as “the go-to network for Barack Obama and Washington's liberal elites,” a clip of Liz Cheney in a 2009 appearance on the network is played.

“In Wyoming, Cheney campaigns as a conservative,” the narrator states in the ad. “In Washington, she appears on MSNBC to campaign against the marriage amendment and support government benefits for gay couples.” (The video is embedded on this page. Visit our video library for more videos.)

However, Cheney announced her opposition to gay nuptials in August.

“I am strongly pro-life and I am not pro-gay marriage,” Liz Cheney said in a statement posted on her website. “I believe the issue of marriage must be decided by the states, and by the people in the states, not by judges and not even by legislators, but by the people themselves.”

The statement provoked a response from her younger sister, Mary Cheney, who is gay and married: “For the record, I love my sister. But she is dead wrong on the marriage issue.”

A spokeswoman for the American Principles Fund, which produced the ad, defended the spot in comments to The Los Angeles Times.

“It's very clear she doesn't support a constitutional amendment” limiting marriage to heterosexual couples, Sanders said. “There's not one thing she would do to protect traditional marriage at the federal level.”