BISMARCK -- First, a series of heterosexual couples kiss. Then, two men are shown about to lock lips. All are dressed for a wedding. That is followed by three people, depicting a wedding of two men and a woman.

The campaign commercial's message: Sen. Byron Dorgan supports gay marriage and unless North Dakotans vote for Republican Mike Liffrig for the U.S. Senate, they can "kiss their morals goodbye."

Democrats demanded Tuesday that Liffrig pull the plug on that ad and another commercial that claims Dorgan supports human cloning, saying the allegations are lies.

The ads began running statewide Monday and will air for two weeks.

Dorgan's campaign co-chairmen, former first lady Jane Sinner and Grand Forks businessman Hal Gershman, issued a joint statement saying: "We know that Mr. Liffrig is inexperienced, but that is not an excuse for his dishonesty."

Vern Thompson, Democratic-NPL Party executive director, said Liffrig falsely claims that Dorgan supports gay marriage. "Michael Liffrig has obviously decided to run a cynical and dishonest campaign," Thompson said.

Dorgan's campaign issued two sheets outlining Dorgan's vote for the 1996 federal Defense of Marriage Act that created a nationwide ban on recognition of same-sex marriage.

Thompson also said Dorgan has publicly supported a North Dakota law passed in 1997 that dictates marriage only between one man and one woman.

Liffrig's campaign manager, Jon Zahm, said the marriage ad is accurate because Dorgan voted in July to block a Senate vote on a proposed constitutional amendment to ban same-sex marriage.

"So we feel that Sen. Dorgan, by not supporting the amendment, that opens the door to other coupling, including multiples coupling," Zahm said.

He said Dorgan's 2002 bill banning human cloning has been interpreted by several national groups, including National Right to Life, as one that would permit human cloning.

Zahm said $40,000 was paid for the two ads and they will rotate for two weeks

"We have other ads and scripts ready to go, too," he said.

He said Dorgan's record shows that he has evolved from a conservative Democrat into a liberal Democrat in the 24 years since he first went to Washington as a congressman.

His change was due in part to his desire to climb to the party's Senate leadership, Zahm said. Dorgan is chairman of the Democratic Policy Committee.

Zahm and Liffrig are both in New York for the Republican National Convention. Zahm declined to make Liffrig available for an interview.

Likewise, instead of making Dorgan available for comments, Dorgan campaign spokeswoman Rebecca Pollard referred questions to Thompson and to the prepared statements and fact sheets.

Robert Uebel of Equality North Dakota, a gay-lesbian rights advocacy group, said Liffrig's marriage ad was no surprise.

"This reflects really the way he's running his campaign," Uebel said. "I think it's a sad commentary on the political process."

He said it would further sour people toward politics.

Dorgan also began running television commercials on Monday, emphasizing his upbringing in Regent.

Dorgan is shown walking in Regent.

He says he's proud to walk through the doors of the Senate on behalf of state residents who work and want good schools and safe neighborhoods.

"That's something I learned right here, something I'll never forget," he says at the end.

Steve Schilling, an assistant professor of history at the University of Mary in Bismarck who has studied North Dakota politics extensively, said he doubts a significant number of voters will stop voting for Dorgan because of Liffrig's ads, even if they agree with Liffrig's social policy views.

"It's not in their best economic interests," he said.

Readers can reach Forum reporter Janell Cole at (701) 224-0830