(Heidi Gutman/ABC)

Hold your horses, Jack Hanna: the Koch brothers just threw a monkey wrench into a May ballot proposal to increase funding for the Columbus Zoo in Ohio.

Less than two weeks from a vote on the proposal, Americans for Prosperity, an interest group financed in part by the conservative Koch brothers, is reaching into the debate over a local tax levy in Franklin County, Ohio.

The move is expected to keep Jack Hanna - the safari-tanned director emeritus of the Columbus Zoo and commonly-known media figure "Jungle Jack" - and his allies busy as a bee in this dog-eat-dog political face-off.

"It's the most curious thing I've ever seen in Franklin County politics," John Kulewicz, co-chair of the movement to pass the tax hike, told ABC News. "Everyone I know is wondering why [the Koch brothers] are getting involved. What does this have to do with anything?"

Much to the chagrin of Senate Majority Leader Harry Reid and other congressional Democrats, Americans for Prosperity has been a major player in U.S. Senate races across the country, taking particular aim at President Obama's signature health care law and Democrats who supported it.

But Eli Miller, the Ohio state director of Americans for Prosperity, said his organization works at the local, state and federal level, and this involvement wasn't uncommon for the interest group.

"A lot of our activists in Franklin County reached out to us on the issue that their voices were not being heard on this tax increase," said Miller. "If you're going to raise taxes at any level, you're going to hear from us."

Americans for Prosperity mailed out ads urging voters to "stop the money grab," featuring a gorilla hand holding a $100 bill. Miller said the group has also gone door-to-door with its campaign.

But Kulewicz said that he doesn't understand why the conservative group is getting involved with an issue that pertains to the zoo's well-being.

"All we know is it's an outside special interest group from northern Virginia with deep pockets," Kulewicz said. "I'm not aware that they have any interest in the zoo at all. I know people in Franklin County are up in arms about it."

Miller wouldn't comment on how much the group has spent so far on the initiative, but said that they "are going to spend as much as it takes to educate Franklin County constituents."

"We decided to help educate the public on this issue so Franklin County residents can decide," Miller said. "As with any tax increase, this is really going to hurt those who can't afford it."