DES MOINES, Iowa (AP) - A national group says Iowa lawmakers are quashing debate on a proposed constitutional amendment banning gay marriage.

Focus on the Family, based in Colorado Springs, Colo., placed ads in Iowa newspapers this week assailing five state senators, including Senate Democratic Leader Mike Gronstal, who the group says are obstructing Iowans' right to vote on the amendment.

Appearing under the headline, "Iraqis Have the Right to Vote, Why Don't Iowans?" an ad in Monday's Des Moines Register took aim at Gronstal, of Council Bluffs.

"When it comes to marriage, the people of Iowa should be seen and not heard," the ad reads. "At least that's the way Sen. Mike Gronstal would have it, as he refuses to let the people of Iowa vote on the Iowa Marriage Amendment."

The ad includes a black-and-white photo, apparently of an Iraqi woman, holding up a single, ink-stained index finger. The finger, which appears in color, has become synonymous with Iraqi suffrage.

In an interview with The Associated Press, Gronstal dismissed the ad as politically motivated.

"Here's an out-of-state group that believes it's perfectly OK to be misleading," he said Thursday. "To be deceptive and put information out like that is completely inaccurate."

A bill defining marriage as being between a man and a woman has cleared the House, where Republicans hold a slim majority. But the bill has not been voted on in the Senate, where each party holds 25 seats. The bill is in the Senate Government Committee.

Peter Brandt, Focus on the Family's senior director of public policy, said the group believes there are enough votes in the Senate to send the amendment to voters. The group decided to target some prominent senators, including Gronstal, Senate Democratic President Jack Kibbie, D-Emmetsburg, Sens. Maggie Tinsman, R-Davenport, Steve Warnstadt, D-Sioux City, and Amanda Ragan, D-Mason City.

"Let the people vote," Brandt said. "This is an important issue and people feel strongly about it. … What are the senators afraid of here?"

Brandt said similar ads are planned in eight to 10 other states.

"We'll be looking at other states where the Legislature decides that it's the final law and not the people," he said.

At least one of the targeted lawmakers, Warnstadt, has said the ad skews his position on gay marriage.

In a report in The Sioux City Journal, Warnstadt is quoted saying he believes marriage is "between a man and a woman." Warnstadt also told the newspaper he is not able to hold up legislation because he is not on the Senate Government Committee.