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Efforts by a third-party organization to tie Barack Obama to the leader of a home-grown terrorist group are being met with stiff opposition from the Obama camp, perhaps demonstrating that Democrats learned their lesson in 2004. Four years ago, John Kerry waited several weeks to respond to ads launched by the Swift Boat Veterans For Truth, by which time the organization's message had already taken hold. This time around, Democrats are not taking any chances.

American Issues Project launched a TV ad last week presenting Obama as "friends" with William Ayers, once a member of the Weather Underground, the now-defunct radical group responsible for bombing the Capitol in 1971. The ad quotes Ayers saying, years later, that the group "didn't do enough," and an announcer says that Obama has nonetheless "defended Ayers as 'respectable' and 'mainstream.'"

"Why would Barack Obama be friends with someone who bombed the Capitol -- and is proud of it?" the announcer asks over ominous music. "Do you know enough to elect Barack Obama?"

The ad also references 9/11, comparing the 1971 bombing to the hijacking of United 93, which al-Qaida may have intended to fly into the Capitol building.

AIP President Ed Martin said that the spot was turned down for national ad buys on Fox News and CNN but is running regionally in several swing states -- including Michigan, Ohio, Virginia and Pennsylvania. According to a letter filed with the Federal Election Commission, it is being financed by Harold Simmons, a Texas billionaire who also contributed to the Swift Boat campaign and is a bundler for John McCain.

As a 501(c)4 nonprofit, AIP is allowed to run ads, but only ones that are not political in nature. Martin explained the group's decision to launch an ad campaign as a response to Obama's decision to forgo public financing and signals from many left-leaning groups that they will spend millions of dollars promoting Democratic causes this cycle.

The subject of Ayers and the Weather Underground, Martin said, did not appear to be getting much play among the mainstream media. "It seemed egregious that there is this recent and ongoing relationship" between Obama and Ayers -- "a strange and in many ways disreputable figure."

But the Obama campaign has attacked AIP's advertising effort as a clear violation of campaign fundraising laws, and campaign attorney Robert Bauer has fired off a series of letters to TV stations running the ad, as well as to the FEC and the Justice Department, even going so far as to call for prosecution of Simmons for his role in financing the spot.

Obama has also launched a response ad in Ohio, though he has done so quietly, not releasing it to the media.

Martin defends AIP's efforts, saying the group "spent a lot of time and resources to do things right" and that he is "very confident we complied with the law." AIP "expected a lot of attention" to be paid to the ad, he acknowledged. "What has been a surprise has been the extent to which the Obama camp has employed... what could be characterized as intimidation or attempted intimidation" in response.

He accused the campaign of engaging in "Stalinist tactics" and argued that it has not responded to the truth of the ad. "The idea of running to the Justice Department, demanding prosecution... it's really beyond the pale. It Smacks of a kind of desperation about the issue that we didn’t expect," Martin concluded.

The dispute is sure to continue. But, as it did when it released a new web site, FightTheSmears.org in response to viral emails spreading rumors about the Illinois senator, the Obama's campaign has proved its firm intention to fight back against any onslaughts from the Right.