Updated

A conservative group with a distinctly pro-American agenda will be signing up thousands of new members, it claims, after President Obama suggested the group was doing the political bidding of foreign corporations.

Leaders of Americans for Prosperity, a national conservative organization that promotes economic opportunity and expressly promotes educating "citizens" about public policy and constitutional limits, say they are flattered the president called out the group by name during a speech to the Democratic National Committee. But, they add, he need not worry about international influence of its 1.2 million members.

"The suggestion that we're anything other than what we claim to be is ridiculous. The substance of the accusation makes no sense," said Phil Kerpen, the group's vice president for policy.

The president singled out the heavyweight organization during a DNC fundraiser in Austin on Monday.

Citing the recent Supreme Court decision that loosened campaign finance rules, he claimed "groups with harmless-sounding names like Americans for Prosperity" could run ads against Democratic candidates with impunity. The concern is that an organization like Americans for Prosperity could dump millions into an election to sway voters without the voters ever knowing who's behind it all.

"And they don't have to say who exactly the Americans for Prosperity are. You don't know if it's a foreign-controlled corporation. You don't know if it's a big oil company or a big bank. You don't know if it's a insurance company that wants to see some of the provisions in health reform repealed because it's good for their bottom line, even if it's not good for the American people," Obama said. "A Supreme Court decision allowed this to happen. And we tried to fix it, just by saying disclose what's going on, and making sure that foreign companies can't influence our elections."

Obama did hit pointedly one aspect of the conservative group. Americans for Prosperity was founded by billionaire David Koch of oil company Koch Industries. Koch and his company, however, are American.

Kerpen said AFP's members and donors are, as the name implies, Americans -- the group says it's signing up thousands more supporters in preparation for the fall.  He said less than 10 percent of the group's donations are from corporations and that about 70,000 individual donors contribute.

Kerpen said the group is shooting to spend about $45 million in this year's election, targeting about 40 House races and eight Senate races.

He added that the president's remarks show he's "concerned" the campaigns are reaching voters.

"He's got to discredit us, sort of shoot the messenger," Kerpen said, calling the Austin remarks "kind of flattering."

Americans for Prosperity blasted out an e-mail to members after the Austin comments and President Tim Phillips released a statement saying Obama was "making shrill, desperate attacks" at a time when his approval ratings are "dropping rapidly."

"The president is losing on the issues. Americans continue to be disenchanted with Obamacare, his uncontrolled spending habits and vain attempts to pass an energy tax. This is why thousands of new activists continue to join Americans for Prosperity every day. President Obama can continue his attacks but that won't change the fact that November is coming," Phillips said.

"November is Coming" is the name of Americans for Prosperity's bus tour which is hosting rallies and training sessions across the country. The campaign is signing up activists to go door-knocking, enlist other supporters and become local organizers. The bus tour so far has antagonized Democrats in Ohio, Pennsylvania and several other states, while Americans for Prosperity is also running ads against targeted candidates.

One ad went up this month against Michigan freshman Rep. Mark Schauer criticizing him for his votes in favor of the health care overhaul. Schauer is facing a rematch this year against the man he defeated in 2008 -- Republican Tim Walberg. The race is listed as a toss-up by Cook Political Report and other oddsmakers.

Americans for Prosperity earns millions in donations, some of it reportedly from other conservative foundations. As a 501(c)(4) organization, the group is not required to disclose the identities of its donors.

A journalist with the Center for Public Integrity said organizations seek that particular status for that reason -- meaning a mix of unnamed corporations and individuals can end up funding such operations.

"Some groups don't want to go through the disclosure process, but I think that they also try to cater to and attract money from donors who don't want their names disclosed," the journalist said.