Billionaire hedge fund manager and green power advocate Tom Steyer is taking Gov. Scott Walker to task, accusing the Republican presidential hopeful of being a pawn for fossil fuel interests and a climate change denier.

In a full page ad running in the Wisconsin State Journal Tuesday, Steyer’s group NextGen Climate blasts the state’s GOP leadership for promoting a “war on science” by banning work on climate change.

The group calls out Walker specifically for staying silent on the issue and for signing a Koch-backed anti-climate change pledge.

“Fossil fuel interests like the Koch Brothers have made millions while opposing solutions to climate change,” the ad says. “They’re protecting their profits by bankrolling Big Oil politicians like Scott Walker.”

Steyer, who during the 2014 election cycle pledged to spend $100 million on environmental issues, has largely ignored Walker to this point. Instead, his advocacy front group has focused on better-known GOP contenders like Jeb Bush, Marco Rubio and Ted Cruz.

But reports last week on a measure to prohibit staff at the Board of Commissioners of Public Lands from engaging in global warming or climate change discussions sparked the ad buy here.

“This is our first paid advertisement featuring Gov. Walker,” said NextGen spokesman Bobby Whithorne in an email. “His decision to remain silent as Wisconsin Republicans wage a war on science clearly signals he wants to be the candidate for the Climate Change Denial Caucus.”

As the campaign moves forward, NextGen Climate has vowed to follow Walker as he visits key presidential states.

Walker spokeswoman Laurel Patrick declined to respond to the NextGen attack, referring any questions to the campaign. She noted the Board of Commissioners of Public Lands is comprised of three statewide constitutional officers and the Governor’s office is not represented on the board and is not involved with board policies.

“With that said, generally, Governor Walker does not think it is unreasonable to enact policies requiring board staff to focus on board-related activities,” she said.

In its statement, NextGen said Gov. Walker has “a long record of promoting the Koch brothers’ economic agenda — and raking in their campaign donations.” It references Walker signing a Koch-backed anti-climate pledge and raising money for the Heartland Institute, a Chicago-based organization that has long questioned mainstream scientific assumptions about global warming.

A native New Yorker now residing in San Francisco, Steyer has come under fire from the right for making some of his money off the Asian and Australian coal markets. He retired from the money management business in 2012 and has an estimated net worth of $1.6 billion.

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