(CNN) -- Kay Hagan erupted in anger Thursday over a television ad from Sen. Elizabeth Dole suggesting Hagan is "godless."
"I think Elizabeth Dole has just gone to the lowest of the lows," Hagan said of the ad during an appearance on a talk show on WPTF-AM in Raleigh, North Carolina. "This is an attack on my Christian faith."
Hagan, who described herself as a Sunday school teacher and an elder at a Presbyterian church in Greensboro, North Carolina, urged Dole to "pull this kind of despicable ad."
Hagan, who is challenging Dole's re-election bid, filed an application in a Wake County, North Carolina, court Thursday, seeking permission to file a complaint within 20 days, after the election is over.
"The advertisement purposely misstates facts about the plaintiff," said the three-page application, which was filed in District Superior Court.
In the 30-second ad, a narrator says that a leader of the Godless Americans Political Action Committee recently held a "secret fundraiser" for Hagan.
The ad then shows members of the group, which promotes rights for atheists and the separation of church and state, declaring that neither God nor Jesus exists.
"Godless Americans and Kay Hagan," the ad continues. "She hid from cameras. Took 'Godless' money. What did Kay Hagan promise in return?"
The ad ends with a picture of Hagan and a voice that sounds like hers declaring, "There is no God."
But the application said Hagan never made that statement or accepted money from the group.
Lawyers representing Dole and her campaign defended the ad Thursday as "100 percent factually accurate and truthful." The campaign for the GOP incumbent said it based its claims on Hagan's attendance at a fundraiser in the home of a GAPAC adviser.
"Kay Hagan attended a fundraiser event in Massachusetts in September held in the home of two anti-religion activists, Wendy Kaminer and her lawyer husband, Woody Kaplan," Dole's attorneys said in a letter to Hagan's lawyer.
They described Kaplan as a founder and advisory board member of the GAPAC. The letter said Kaplan and Kaminer were advisory board members of The Secular Coalition for America, which it described as "the national lobby for atheists, humanists, freethinkers and other nontheistic Americans with the unique mission of protecting their civil rights."
The lawyers also said Kaplan gave $2,300 to Hagan's campaign.
"This is politics of the worst kind, and I know it has been rejected by North Carolinians at every level," said Hagan.
Polls suggest Hagan -- a Democratic state senator from Greensboro who began the race at a major financial disadvantage to Dole -- is slightly ahead of the incumbent.