You almost can't tell it's an attack on Mitt Romney.

In the television ad, the music is uplifting, the feminine narrator speaks firmly but sweetly. In the excerpts from his speeches, Romney looks and sounds like a man in command. There are lots of American flags.

But the rich production values conceal a sly assault. All of the positions Romney declares in the ad, on abortion and gun control, are views he no longer holds. The ad never acknowledges its real point, which is to mock Romney's abandonment of his moderate Republican past as he seeks the mantle of social conservative in the Republican presidential primary.

The ad's creator is the Log Cabin Republicans, a group of gay and lesbian Republicans who push the party to be more inclusive. Its purpose is to let other Republicans know that Romney is a big phony, said Log Cabin president Patrick Sammon.

"The issue here is about trust; it's about character; it's about principle," Sammon said. "Mitt Romney has real challenges on all those issues. The lesson for Republicans is they need to be honest about what they believe."

Interestingly, the ad doesn't mention any gay and lesbian issues. As a presidential candidate today, Romney favors an amendment to the U.S. Constitution to ban same-sex marriage. As a candidate for office in his home state of Massachusetts years ago, he campaigned for gay and lesbian support, emphasizing his opposition to discrimination in the workplace.

"Certainly Governor Romney used to be supportive of gay rights, but I'm not sure anyone knows what he supports now," Sammon said.

The ad, which Sammon said has aired in Iowa and nationally on Fox News, uses Romney's own words against him, showing video clips of Romney from a 1994 debate against incumbent Democratic Senator Ted Kennedy.

It comes on the heels of another YouTube video called "The Real Romney?", which features extended footage of Romney arguing for moderate social positions during the 1994 debate. The video, which has over 200,000 views, was posted anonymously, but its authenticity has not been challenged.

Log Cabin Republicans are not endorsing a candidate in the Republican primary. But if their attack on Romney helps anyone, it probably would be Romney's fellow frontrunner Rudy Giuliani, who has supported gay issues in the past and hasn't changed his previous positions to the extent that Romney has.

"There is a school of thought that says Giuliani is the most favorable of the Republican candidates for gay rights," said Chuck Wolfe, president of the Victory Fund, which supports openly gay and lesbian candidates. "But I think a lot that is a feeling more than a track record."

Could the Log Cabin Republicans have other motives for attacking Romney? Sure, said Stuart Rothenberg, who edits the independent Rothenberg Political Report in Washington, D.C. "They're probably doing it for several reasons, to raise money, to show their contributors they're doing something, all those things."

Sammon won't say whether donations have increased since the ad started running.

As to whether the Log Cabin attack will hurt Romney, it's still too soon to say, said Rothenberg: "So far, conservatives seem to be saying, 'He was running in Massachusetts, he had to sound like a liberal.'"

But Giuliani, who is running as a social moderate in the same GOP primary, is a popular candidate as well. It's surprising that Romney isn't taking more heat for switching positions, and that Giuliani is getting serious support without renouncing his moderate social views, Rothenberg said.

"The jury's still out," he said. "It's a very surprising race."