LANSING, Mich. (AP) — The group Americans for Prosperity backed by the billionaire Koch brothers is spending nearly $1.7 million on a television ad that criticizes Democratic gubernatorial candidate Gretchen Whitmer, saying she backed policies of former Gov. Jennifer Granholm and voted for tax increases as a legislator.

The 30-second ad will begin airing Thursday and will run for three weeks — an early buy considering the general election is five months away. The launch comes the same week a pro-Whitmer political group began a $1.8 million, five-week ad campaign — the first time she is introducing herself to viewers before the August primary.

The ad points to Whitmer's 2007 votes to raise the income tax, expand the sales taxes to some services — a move she and others quickly helped to scrap by increasing a business tax— and a 2014 vote to boost fuel taxes. The 2007 votes came as Granholm, a Democrat, and the Legislature faced major budget deficits and a government shutdown during an extended recession.

"The failed policies that defined Granholm's lost decade were championed by Whitmer, not all Michiganders. We don't need more of the same," Pete Lund, the director of the conservative organization's Michigan chapter, said in a statement. The group last month launched a six-figure digital ad and direct mail campaign targeting the former Senate leader.

Whitmer spokesman Zack Pohl said she "took on" Granholm repeatedly in Lansing, citing votes against early retirement incentives for teachers, cuts in health care benefits for retired educators and a tax change resulting in less revenue for the school aid fund.

"The billionaire Koch brothers are attacking Gretchen because they know she's the strongest candidate to beat (Republican) Bill Schuette in November," he said in statement, calling the attack ad "a distraction from the conversations that really matter to hardworking Michigan families, like how to fix the damn roads, create good-paying jobs and make health care more affordable."

Whitmer is running in a three-candidate primary that also includes self-funding businessman Shri Thanedar and former Detroit health director Abdul El-Sayed. She has won the backing of many labor unions, elected Democrats, Emily's List and other groups.

Schuette, the state's attorney general, is in a four-way primary with Lt. Gov. Brian Calley, state Sen. Patrick Colbeck and Dr. Jim Hines. He has linked both Whitmer and Calley, who also served in the Legislature, to Granholm-era tax changes.

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