When Donald Trump won New Hampshire, he won it in two ways: He won the most votes, while the establishment was divided by a split result among its ranks.
Tonight,Mr. Trump won with nearly the same share of the vote. But he might lose once and for all what has been his biggest advantage: the divided Republican field.
With 99 percent of the vote reporting, Mr. Rubio holds 22.5 percent of the vote. It might not seem an impressive figure, but it meant he finished well ahead of Mr. Bush, who holds just 7.8 percent of the vote. It was enough to force Mr. Bush out of the race.
It is hard to overstate how important Mr. Bush's departure is to Mr. Rubio. No, Mr. Bush did not hold a large number of votes (though I would note that the sum of Mr. Rubio and Mr. Bush's support would have been very close to Mr. Trump's total, and well ahead of Mr. Cruz's).
But he held a large number of donors and officials in his camp, and he kept as many or more on the sidelines. His presence prevented any other Republican from consolidating the power of the mainstream wing of the party. The fighting among the mainstream Republicans hindered them from focusing an attack on Mr. Trump.
The combination of Mr. Rubio's strong showing and Mr. Bush's exit could bring about a "party decides" moment — the rapid consolidation of the mainstream of the Republican Party. It could mean a flood of endorsements and donations to Mr. Rubio ahead of Super Tuesday on March 1.
The benefits to Mr. Rubio could be huge. He will have more endorsements, more money, and he will now be free of the attacks from the Jeb Bush super PAC Right to Rise and his other mainstream rivals. He will have more votes available as well.
Mr. Bush's exit would be enough to make tonight a win for Mr. Rubio, but Mr. Rubio's share of the vote is impressive as well. Most important, he cleared 20 percent of the vote — a crucial delegate threshold for many Southern states on Super Tuesday (although not South Carolina tonight). If he can't exceed that number in states like Alabama, Texas, Georgia and Tennessee, he will receive no delegates in those states. It's a good sign that he's near or above this number even after the disadvantage of a divided field and after a weak showing in New Hampshire.
The number of votes at stake is potentially considerable: Mr. Bush and Mr. Kasich currently combine for 15.4 percent of the vote, and that support would seem likely to break toward Mr. Rubio.