Ken Koeppe wears tea bags on his hat during an Americans For Prosperity rally.National Journal

ORLANDO—At 9 a.m. on a recent Wednesday, volunteers and staff already had packed the anonymous-looking suburban house that serves as Americans for Prosperity's local headquarters. They fueled up on coffee and breakfast pastries before venturing out in the already-beating sun, nearly a year and half before the next big election, to knock on conservative voters' doors.

AFP, one of the main arms of the Koch brothers' conservative political machine, is best known for its corporate titan founders and multi-million-dollar ad campaigns blasting congressional Democrats. The nonprofit helped GOP candidates up and down the ballot win elections in 2014, and you could practically hear Democrats biting their nails when the Kochs revealed their network's 2015-2016 budget: a whopping $889 million.

But on that Wednesday, AFP's volunteers were mobilizing against a Republican, blasting state Senate President Andy Gardiner's proposal to take federal funds to put more low-income Floridians on Medicaid. The volunteers, armed with brochures and scripts (as well as lots of chilled Gatorade and water) were knocking on doors here in the hopes of driving conservatives to register opposition to the plan.

It's part of nationwide trend: AFP has spent 2015 raising hell in GOP-dominated statehouses, where the group feels some Republicans have strayed from conservative principles.

Florida and 22 other states have both Republican governors and Republican-controlled legislatures, but that doesn't mean they always pass legislation harmonioiusly. AFP is battling with them over Medicaid expansion (in Florida, Tennessee and elsewhere), proposed increases to the gas tax, tax credits for the film industry and a host of other issues.

"This entire year is about holding accountable Republican majorities," Tim Phillips, Americans for Prosperity's president, said in an interview. "They are doing some good things too. But we're doing an enormous expansion of spending and staff time toward holding Republican legislative majorities accountable on issues."

In that light, the enormous poster of Martin Luther King, Jr. in AFP's local headquarters takes on special meaning. The quote beneath King's picture reads: "In the end, we will remember not the words of our enemies, but the silence of our friends."

But nowhere is AFP's fight with Republicans more intense right now than in Florida, where the politicians they are targeting are largely Republicans.

Chris Hudson, AFP's Florida state director, is not shy about touting his group's influence. Lawmakers "see people in their offices wearing buttons with little green torches, and they think, 'I'm about to find out what my 2015 legislative agenda is,'" Hudson boasts.

Tallahassee is packed with powerful lobbyists and legislators who might disagree, but AFP still argues its efforts are bearing fruit. The push for Medicaid expansion has gotten less likely as time has gone on, with Republican Gov. Rick Scott issuing veto threats and some initial business support fading. In the meantime, AFP says it has knocked on over 40,000 doors during the legislative session to oppose the expansion and other issues. When the Florida legislature was considering a bill to provide tax incentives to filmmakers, the group incited 42,000 activist emails worth of outrage to legislators, and the bill died during the regular legislative session.

AFP recently opened its 12th field office in the state, its biggest presence anywhere in the country. Hudson says the established offices regularly have 25 to 50 volunteers coming through the doors to help out. And there are more staffers working in "floating" offices without a permanent location as the group's reach grows.

AFP does more traditional lobbying sometimes, sending its activists to Tallahassee to buttonhole lawmakers, and it spends money on a variety of mailers, radio ads, and TV spots—like a version of this anti-Medicaid ad that started running on TV last week. But pulling together the people who make those phone calls, or eventually become volunteers, is a laborious and sometimes unrewarding process.

On that recent Wednesday morning, a set of AFP canvassers in Gardiner's district encountered more cats than people. Many doors are marked with "no solicitation" signs. Those who answer the door aren't always friendly.

In one instance, AFP's targeting appeared to have missed the mark: "I'm a Rhode Island-raised Democrat," one Obamacare supporter said at his door. "Still want to talk?" On other occasions, AFP organizer Alisa Ardiles said, she'd been menaced. "I had someone threaten to shoot me last year," she said. "He thought we were Communists because of the flame symbol. I said, 'sir, I cannot stress enough that we are not.' You meet some characters."

But the targeted door-knocking does bring people into the fold. At one door, Ardiles encountered a woman who hadn't heard of Medicaid expansion before but pledged to call Gardiner's office after hearing Ardiles's pitch. The Medicaid program was already creaky, she said, and it couldn't handle one million more patients—especially if the state would eventually have to take over the cost.

"I think you're right," the woman finally said, promising to use the information to call Gardiner's office. So did several others who answered their doors that morning.

AFP's work hasn't dissuaded the Senate, which last week passed Gardiner's new plan nearly unanimously. But it ran aground in the House last week, where hardline position against the expansion had looked more and more likely to win over the last few months.

"I would have said eight weeks ago I didn't understand what the House was doing," said Tre' Evers, a Republican consultant from Orlando. "But AFP has successfully branded this around Obamacare, and as a fight opposing that."

Moreover, the grassroots work AFP does on policy issues helps build its growing volunteer base. Some eventually join as part- or even full-time staff members, fueling the growth that has AFP-Florida looking at new places to establish field offices.

Part of their door-knocking program is designed to encourage contact with potential volunteers, who would then help recruit more volunteers. At other times, the focus might be on politics over policy, which has its own ways of bringing more people in. Then, by the next legislative session, there are even more volunteers to push issues before lawmakers.

"People are just shocked to find out this isn't a go-away operation," said Chris Hudson, AFP's Florida state director. "We have diehard activists who work year-round."

Gardiner, their chief opponent on Medicaid expansion, is less sure of their influence. "I don't know how big their presence is," Gardiner said in an interview. "Certainly everyone knows their connection with the Koch brothers, and they've done some mail in my and some other areas. But both sides are advocating and doing mail. It doesn't bother me. And God bless 'em for participating in the process."

Other Republican legislators get more volatile about AFP. State Sen. Nancy Detert was one of the Republicans pushing the film tax incentives earlier this year. "I hope you are getting paid a lot of money to show up to these meetings and say meaningless things," Detert said, on camera, to an AFP rep opposing the bill. "Obviously, you are for prosperity for yourself, and not other people in the industry."

Next year, when the presidential race, a major U.S. Senate campaign, and more political activity ramps up in the nation's biggest swing state, AFP's energies will shift once again to criticizing Democratic policies and sometimes directly advocating for GOP candidates. But for now, they're working to pull their own party to the right.

Andres Malave, AFP's Florida communications director, says the group's willingness to take on Republicans and conservatives confounds some. "They don't know how to turn it off because we're not beholden to any interest as usual," Malave said.

But officials calling on AFP to ease off in the name of pan-Republican solidarity are fast finding out that the group pulls no punches—not for party, and not even for family. When AFP-Florida released its annual "economic freedom scorecard" for legislators in 2014, Hudson's own father, GOP state Rep. Matt Hudson, got a middling "B" grade.

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