IOWA CITY, Iowa (AP) — Republican presidential hopeful Herman Cain has cast himself as the outsider, the pizza magnate with real-world experience who will bring fresh ideas to the nation's capital. But Cain's economic ideas, support and organization have close ties to two billionaire brothers who bankroll right-leaning causes through their group Americans for Prosperity.

Cain's campaign manager and a number of aides have worked for Americans for Prosperity, or AFP, the advocacy group founded with support from billionaire brothers Charles and David Koch, which lobbies for lower taxes and less government regulation and spending. Cain credits a businessman who served on an AFP advisory board with helping devise his "9-9-9" plan to rewrite the nation's tax code. And his years of speaking at AFP events have given the businessman and radio host a network of loyal grassroots fans.

The once little-known businessman's political activities are getting fresh scrutiny these days since he soared to the top of some national polls.

His links to the Koch brothers could undercut his outsider, non-political image among tea party fans who detest politics as usual and candidates connected with the party machine.

AFP tapped Cain as the public face of its "Prosperity Expansion Project," and he traveled the country in 2005 and 2006 speaking to activists who were starting state-based AFP chapters from Wisconsin to Virginia. Through his AFP work he met Mark Block, a longtime Wisconsin Republican operative hired to lead that state's AFP chapter in 2005 as he rebounded from an earlier campaign scandal that derailed his career.

Block and Cain sometimes traveled together as they built up AFP: Cain was the charismatic speaker preaching the ills of big government; Block was the operative helping with nuts and bolts.

When President Barack Obama's election helped spawn the tea party, Cain was positioned to take advantage. He became a draw at growing AFP-backed rallies, impressing activists with a mix of humor and hard-hitting rhetoric against Obama's stimulus, health care and budget policies.

Block is now Cain's campaign manager. Other aides who had done AFP work were also brought on board.

Cain's spokeswoman Ellen Carmichael, who recently left the campaign, was an AFP coordinator in Louisiana. His campaign's outside law firm is representing AFP in a case challenging Wisconsin campaign finance regulations. At least six other current and former paid employees and consultants for Cain's campaign have worked for AFP in various capacities.

And Cain has credited Rich Lowrie, a Cleveland businessman who served on AFP's board of advisors from 2005 to 2008, with being a key economic adviser and with helping to develop his plan to cut the corporate tax rate to 9 percent, impose a national sales tax of 9 percent and set a flat income tax rate of 9 percent

"He's got a national network now that perhaps he wouldn't have had 15 or 20 years ago because of his work with AFP," said Republican Party of Wisconsin Vice Chair Brian Schimming, who has introduced Cain at events in Wisconsin. "For a presidential candidate, that's obviously helpful to have."

He said Cain was smart to hire Block.

Cain's recent victories in straw polls in Florida and Minnesota highlight the importance of organizing supporters and Block, who has a deep network in the tea party, "gets that side of it," Schimming said.

But Block has had his problems as well. He settled a suit in 2001 accusing him of illegally coordinating a Wisconsin Supreme Court justice's re-election with an outside group. Block agreed to pay $15,000 and sit out of politics for three years.

While Cain is quick to promote his career at the helm of the Godfather's Pizza chain, his ties to AFP aren't something the candidate appears eager to highlight.

His campaign did not respond to inquiries seeking comment, and Cain does not include his AFP work on his biography on his website.

But Cain continues to work with the group.

While several other candidates will be at an Iowa Republican Party dinner on Nov. 4, Cain is scheduled to be in Washington mingling with activists at AFP's annual "Defending the American Dream" summit. He is the only confirmed presidential candidate for the event.

AFP spokesman Levi Russell said Cain has spoken at dozens of AFP rallies and events over the years to support a number of the group's activities. AFP has often covered his travel expenses or paid a "pretty modest honorarium" but he has not been paid since becoming a presidential candidate, he said.

"He's a dynamic, pro-business speaker that connects well with our activists," Russell said. "AFP is a very large organization, and there is a natural overlap between Cain's message of fiscal responsibility and the basic principles that AFP advocates for."

A spokeswoman for the Koch brothers did not respond to The Associated Press's request for comment on Cain.

To some liberals, Cain's rise with the help of AFP shows the incredible influence that outside groups controlled by super-wealthy individuals with specific agendas can have on the political process.

"Herman Cain is the first presidential corporate spokes-candidate," said Scot Ross, a liberal activist who leads One Wisconsin Now, which has often mocked AFP as a front group for corporate interests. "The best way to have your issues talked about in the issue debate is to have a candidate in your pocket with snappy comebacks and easily branded policy papers which mask how destructive they would be."

AFP's agenda also includes weakening private and public sector unions, opposing environmental regulations and undoing Obama's health care reform law, among other policies. But before the tea party and Obama, Cain worked with AFP on more local issues.

In 2006, he campaigned all over Wisconsin in support of a proposed constitutional amendment that would have limited state government spending. A slew of officials and analysts said the plan would have ultimately devastated government services, and the Republican-controlled Legislature eventually backed off it.

In a statement announcing Cain's tour, AFP sent out a press release touting his "in-depth understanding of the battle to control out-of-control government taxes and spending." Block promised that Cain was a speaker that activists would not want to miss.