For months, mainstream Republicans have hoped that Donald Trump’s support was a mirage — a combination of high name recognition, unsustainable news media coverage and support from irregular voters who might not show up in a primary.

Tonight, there’s reason to believe their hopes just might be well founded. Despite leading each of the last 10 Iowa polls, by an average of seven percentage points, Donald Trump was defeated by Ted Cruz, who currently leads, 28 percent to 24 percent, with 97 percent of precincts reporting in the Iowa caucuses. Marco Rubio is in a strong third place with 23 percent of the vote.

In the end, Mr. Trump came closer to taking third than to winning.

The result doesn’t necessarily leave us much closer to knowing who the eventual nominee will be. It probably signals the beginning of a protracted, three-way fight for the nomination. But the loss raises the possibility that Mr. Trump’s strength is at least partly an illusion; he may not be quite as strong as he looks.

Mr. Trump’s defeat won’t necessarily derail his campaign, as some have speculated. He leads by a wide margin in polling in New Hampshire, so he’ll have a strong opportunity to rebound.