The night could not have gone much worse for Marco Rubio, perhaps the only Republican with a good chance to beat Mr. Trump in a one-on-one contest. He failed to win Virginia, his best prospect of a primary victory. He has won in Minnesota, but it will be hard for him to claim any great strength with one caucus win in what was already poised to be his best state.
Even worse for Mr. Rubio was the strength of his opponents. Ted Cruz won Texas and neighboring Oklahoma, giving him more wins than anyone else in the race except Mr. Trump. Mr. Cruz did not finish in a distant third elsewhere in the South, as seemed possible soon after South Carolina.
Between his own failings and Mr. Cruzs strength, Mr. Rubio seems likely to be in a distant third place in the delegate count after tonight. Mr. Rubio is also in danger of missing crucial delegate thresholds in Texas, Vermont, Alabama and perhaps Tennessee.
Making matters worse for Mr. Rubio is that John Kasich, who has very little support nationwide, nonetheless managed to defeat him in Vermont and might still do so in Massachusetts. Mr. Kasich won 9 percent of the vote in Virginia, probably throwing the state to Mr. Trump. His support was strongest in places like Northern Virginia, where Mr. Rubio fared best.