Their confidence is rooted in the fact that Trump and Cruz are nearly certain to control the lion’s share of the 2,472 delegates participating in the July convention. Together, they’ve earned more than 1,000 delegate slots to Kasich’s 136. And those delegates will ultimately approve the rules that govern a contested convention.

In addition, a rule adopted at the 2012 convention — pushed by supporters of Mitt Romney to box out Ron Paul — requires that any candidate eligible for the nomination win the majority of delegates in eight states or territories. In 31 contests so far, Kasich’s only win came Tuesday night in Ohio — his home state — and it’s unlikely he’ll command majority support in seven of the remaining 20 contests.

To be sure, the convention rules will get a thorough review and revision when delegates convene in Cleveland, raising the possibility that the threshold to participate could be lowered, making room for Kasich. But with Trump and Cruz delegates at the helm, it’s unlikely they’ll adjust it to help a rival.

“The Cruz folks would never allow the rules to be changed and of course we wouldn’t either,” said Barry Bennett, who’s coordinating Trump’s convention strategy. “The laws of math are not amendable.”