Raleigh, N.C. — Americans For Prosperity, a conservative group backed by billionaire brothers David and Charles Koch, will make a direct appeal for voters to oppose President Obama in a series of ads that begins airing in North Carolina and elsewhere Wednesday.

The ads represent an important shift for the group, although it's one that voters may not notice right away. 

AFP is a 501(c)4 organization, a tax code designation used by "social welfare" groups. Such groups don't have to reveal their donors but, due to distinctions in federal tax and election laws, typically haven't advocated directly for the election or defeat of a candidate.

Prior ads by the group have been hostile to the president and urged voters to contact the administration. But they avoided so-called "magic words" such as "vote against" or "elect" that would have legally made the advertisements campaign ads. 

This latest AFP ad appears to remove that particular fig leaf. It targets the expansion of the national debt under Obama and ends with, "Let's make this a one-term proposition on November 6th" displayed on the screen.

“We don’t take this lightly,” Tim Phillips, president of Americans for Prosperity, told The New York Times earlier today. “We’ve always stayed away from express advocacy. But given the president’s disastrous record, we felt this was necessary.”

AFP is scheduled to hold a conference call with regional reporters this afternoon regarding the ad, which will run in North Carolina and 10 other states.

"Over the past eight years, Americans for Prosperity has never advocated the election or defeat of any candidate choosing instead to focus on issue efforts. But the stakes for our nation are too high," said Dallas Woodhouse, who heads the North Carolina chapter of AFP. "President Obama's big government economic policies are harming our nation's prosperity by driving up taxes, increasing wasteful government spending and debt and killing jobs with a regulatory assault led by the EPA while demonizing our nation's job creators."

He added, "In an unprecedented action for Americans for Prosperity, our organization will be purchasing paid media time to expressly advocate the defeat of President Barack Obama with a television, radio and social media effort launching on Wednesday, Aug. 8. This effort will be separate from AFP’s grassroots mobilization effort, which will continue to drive grassroots pressure on President Obama’s policies and will not weigh in on the election."

Update: AFP will spend $6.7 million on the ad this week, $850,000 in North Carolina this week. "We expect to spend $25 million to $27 million before Labor Day," Woodhouse said.

The effort could push AFP into a legal situation where it could be forced to reveal its donors and report more clearly on its spending. One person knowledgeable about the move suggested that it was partially prompted by recent rulings in Van Hollen vs FEC, a case brought by a Maryland congressman pushing for greater disclosure by politically active 501(c)4 groups.

Update: Adam Skaggs, senior counsel with the Brennan Center, explains that the Van Hollen decision actually was meant to compel greater disclosure by political groups, but only those who engage in issue advocacy.

Those that engage in express advocacy -- urging voters to support or oppose a candidate -- still fall under an old FEC regulation that allows them to shield their donors. That means AFP is likely the first of several groups that will be more on-the-nose with their political advertising.

"We're going to see a lot more of this express advocacy, which is kind of ironic," Skaggs said. 

Update: Tim Phillips, AFP's national president, said on a conference call that the group has looked at the Van Hollen decision but it was not pivotal in making the change.

"This is something we've been discussing internally for a long time," Phillips said, although he declined to detail that decision making process.

However, Phillips was asked a key question: will AFP disclose its donors due to this ad.

"Under the law, we would not have to disclose our donors," he said. That would, oddly, not be the case if AFP had stuck to the issue ads that it had been doing. 

So even if you take at face value the assertion that this is a long-considered decision, the fact that the change was made allows AFP to stick to its long-standing practice of not disclosing who bankrolls the ads.