OSHKOSH, Wisconsin (AP) — Donald Trump is planning to make his first campaign visit to Wisconsin on Tuesday, where the upcoming Republican presidential primary could mark a turning point in the unpredictable GOP race.

But rival Ted Cruz has gotten a jumpstart on the contest. He’s racking up influential endorsements, campaigning in key regions and supported by bullish advertising campaign.

A solid Cruz win in Wisconsin would narrow Trump’s path to the nomination and heap pressure on the billionaire to sweep the remaining winner-take-all primaries this spring. It also would increase the chances of a contested party convention in July.

Cruz tells The Associated Press “the results in Wisconsin will impact significantly the primaries to come.” He’s positioning himself to win the first primary since he began collecting the backing of establishment Republicans.