RALEIGH, N.C. — Democratic U.S. Senate candidate Kay Hagan on Thursday sued Sen. Elizabeth Dole after the Republican refused to stop airing an ad questioning Hagan's faith.

Hagan also rolled out her own television ad Thursday in which she tells voters "I believe in God" and cites the Bible's Ninth Commandment to decry her rival's tactics.

Dole's ad questions why Hagan went to a fund-raiser at the home of a Boston man who serves as an adviser to the Godless Americans Political Action Committee, an atheist advocacy group.

The ad ends by showing a picture of Hagan while another woman declares in the background, "There is no God."

"Elizabeth Dole's attacks on my Christian faith are offensive," Hagan says in her ad. "She even faked my voice in her TV ad to make you think I don't believe in God. Well, I believe in God. I taught Sunday School. My faith guides my life, and Sen. Dole knows it."

Referring to the Ten Commandments, Hagan concludes her response by saying the campaign is about creating jobs and fixing the economy, "not bearing false witness against fellow Christians."

Dole said the ad does not question Hagan's faith, only her agenda and associations.

"All I know is that she was willing to travel to Boston, and it was done in a way that, I think, she didn't want people to know about it," Dole said.

Hagan's campaign had demanded that Dole stop airing her ad, and they followed through on their threat of legal action, filing paperwork in Wake County Superior Court as a prelude to a libel and defamation suit.

Dole's campaign called the suit "frivolous" and said they would try to get it dismissed.

Dan McLagan, a Dole spokesman, said the campaign had no plans to pull the ad from the air, calling Hagan's promise of a lawsuit an empty threat aimed at distracting voters.

"The ad will be up until it reaches its saturation point," McLagan said.

The dispute comes amid a tight race leading up to next Tuesday's election.

A WRAL News poll released Wednesday showed Dole holds a 46 to 42 percent lead, with 9 percent of voters still undecided. A different polling firm said Thursday that Hagan has a 52 to 46 percent lead.