Republican presidential candidate Ted Cruz greets supporters. (Nam Y. Huh/Associated Press)

GREEN BAY, Wis. -- The big political question in Wisconsin during the past week has been whether Ted Cruz can defeat Donald Trump in Tuesday's Republican presidential primary. The strategy Cruz and his allies are using suggests the answer may rest in no small measure on how John Kasich does.

Cruz released his first TV ad attacking Kasich in Wisconsin over the weekend. The spot, which was first reported by CNN on Sunday, portrays the Ohio governor as being cozy with a corporation that received undeserved state tax breaks. The commercial arrived as the pro-Cruz Trusted Leadership PAC had just introduced an ad slamming Kasich for expanding Medicaid under President Obama's health-care law -- after hitting him days earlier with a spot accusing him of having a "liberal record."

The attacks illustrate the extent to which Cruz and his backers see Kasich as an obstacle in Wisconsin, even if he stands little chance of winning the state. Recent polls show Cruz, a senator from Texas, leading Trump in Wisconsin -- with Kasich a distant third.

"Despite having no path to the nomination, Kasich insists on continuing his quixotic auditioning tour to become Donald Trump's vice president," Cruz spokeswoman Catherine Frazier said when asked why the campaign opted to spend money hitting the Ohio governor. "So far, his greatest strength has been anonymity -- we're simply shining some light on his record." The campaign did not send out a press release announcing the ad.

"Ted Cruz is recycling failed Democrat attacks in a desperate effort to smear Gov. Kasich," responded Kasich spokesman Rob Nichols. "It didn't work for dishonest Ohio Democrats in 2014 and won't work for deceptive Ted Cruz now. Ohioans know that the governor has no say in what companies receive tax credits and they also know Ohio has created more than 415,000 jobs since Gov. Kasich took office."

At a rally here Sunday where he was joined by Wisconsin Gov. Scott Walker, Cruz framed the contest as a two-man race.

"There are two candidates and only two candidates that have any plausible path to winning the Republican nomination: me and Donald Trump," he said.

In between cheers and bellows of "Cruuuuuuuzzzzz" from supporters, the senator argued that he is more electable than Trump. He said that if Trump became the nominee, it would be a "train wreck" for the Republican Party.

"And that's not fair to train wrecks," Cruz said.

But even as he has devoted his attention to Trump on the campaign, it's clearer than ever that Cruz considers Kasich either a rising threat or a candidate leaking or potentially leaking support that he is well-positioned to claim.