A tea-party-linked group whose backers have not been publicly disclosed is circulating an anti-tax pledge at the Statehouse against Republican Governor John Kasich's proposed severance tax increase on oil and gas drillers. The revenue would be used to fund an income tax cut. Founder Chris Littleton tells The Associated Press the nonprofit group "Ohio Rising" is an independent grassroots organization, and signers of the pledge will not be disclosed until there's critical mass. An AP review found several conservative national groups backing the effort have received "energy education" grants from the American Petroleum Institute, an industry organization. Republican State Representative Andy Thompson says he signed the pledge because he believes the proposal could hurt the drilling industry.