The problem is the limited appeal of Trump’s rivals. And Kasich is the primary culprit.

Cruz has had consistent success with a specific segment of the GOP electorate: evangelical and very conservative voters. The Texas Senator has delivered critical wins in states like Wisconsin when the #NeverTrump forces have arrayed behind him. The same can’t be said for Kasich, who has repeatedly failed to perform in the more moderate Midwestern and Northeastern states where he was supposed to be a more viable alternative to Trump.

Again and again, Kasich’s allies have trumpeted the next stretch of the nominating contest as the moment when the Ohio governor would finally find himself on favorable terrain. While Cruz was battling Trump in the South ahead of the March 1 SEC Primary, Kasich planted his flag in more moderate Michigan — only to finish third. On March 15 he slipped to third again in Illinois, another Midwestern state where his allies had promised success.

Even a week ago, Kasich’s advisers were touting his prospects for success on Tuesday. “Ted Cruz’s brand of politics simply won’t play with most voters in Connecticut, Rhode Island, Delaware, Pennsylvania and Maryland,” Kasich strategist John Weaver said last week. NeverTrump PAC, one of the groups exhorting GOP voters to throw their support behind the candidate likeliest to topple Trump in each state, urged Republicans to support Kasich in three of the night’s five states. (In a fourth, Rhode Island, Trump’s lead was so wide that the group didn’t bother issuing a suggestion.) In early returns, Trump was doubling Kasich’s vote share in each of those states.