Byron York of the Washington Examiner probes the potential political impact of the feud between Republican presidential nominee Donald Trump and former primary rival John Kasich.

The Trump-Kasich spat is more than a sideshow. It’s at the very heart of the presidential campaign. Of the various ways, none of them easy, for Trump to win the White House, the most direct is: Win all the states Mitt Romney won in 2012, and then, on top of that, win Ohio, Pennsylvania and Florida. Any other path starts to get really complicated. So a Republican who loses Ohio loses the presidency.

This fall, and especially in October, the GOP presidential candidate will need a huge assist from the Republican power structure in Ohio. He simply has to have it. And at the moment it looks very much like that won’t happen.

“The governor has said that the nominee has to have a positive, inclusive vision, and unless there is a Saul-on-the-road-to-Damascus conversion, he is not going to support [Trump],” Kasich spokesman Chris Schrimpf told me in a phone conversation Tuesday. “Whatever happens in Ohio for Donald Trump is a choice that Donald Trump will make, based on how he chooses to campaign.”

The feud started as bad blood during the primary campaign. It continued after Kasich dropped out and refused to support Trump. And now, Kasich has made history by boycotting his own party’s convention in his own state.