The conservative group Americans for Prosperity (AFP) is launching a six-figure TV ad buy in Wisconsin, urging support for Gov. Scott Walker (R) in the state's ongoing budget standoff.

The TV buy, which will run the group $342,200 over the next week, ups the ideological stakes of the budget battle, with organized labor already panning AFP as a pawn of Koch Industries.

The company is run by billionaire Republican donors, the Koch brothers, who help fund the group and donated heavily to Walker's gubernatorial campaign.

"Who decides Wisconsin's future?" the ad asks. "Voters or government unions?"

The ad includes a still photo of a protest sign that reads, in part, "Scott Walker = Adolf Hitler."

"Democratic legislators refuse to show up for their jobs, hiding out in other states," the ad's narrator says. "And incredibly, President Obama backs the union bosses and floods Wisconsin with out-of-state union protesters."

The launch of the ad comes the same day audio of a phone conversation between Walker and a liberal blogger who posed as David Koch was posted on a liberal website.

The prank call is the latest incident in the high-profile battle over Walker's budget plan. It quickly made its way around the Web on Wednesday, and Walker's opponents pounced on the contents of the call, saying it shows Walker is stubbornly pursuing his budget-fix bill at all costs.

In the call, Walker openly discusses ways to lure state Senate Democrats back to the state capital of Madison to bring the upper chamber back into session, which would likely allow passage of the legislation.

—Jordan Fabian contributed.