(CNN) Ted Cruz's campaign is opening the opposition research book on John Kasich, launching their first negative ad against him before the primary in Wisconsin.

In a new spot that began airing on Wisconsin television on Saturday, Cruz's campaign is taking aim at a company, Worthington Industries, and suggesting unsavory ties to the Ohio governor. The advertisement seems to reflect a strategic shift by Cruz's aides that Kasich poses some threat to Cruz in Wisconsin -- or that his voters are at least up for grabs.

The spot implies that Kasich awarded the company hundreds of thousands of dollars in tax breaks because they paid him money before he won the governorship -- which has not been proven. A state ethics panel in 2013 declined to investigate the potential conflict of interest, which was pushed by Kasich's eventual opponent for governor in 2014.

It does accurately point out that the Worthington Industries chief executive, John P. McConnell, has been a Kasich supporter and that the company fired some employees last year.

"The company laid off 100 Ohioans even as the CEO cut a half-million dollar check to Kasich's super PAC," the spot claims. "John Kasich's not for us."

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