That now goes for Iowans, who handed the braggadocious billionaire a crushing second-place finish last week.
But it looks like Michigan Republicans might just agree with Trump. While many pundits were smugly writing The Donald's political obituary and lavishing attention on "establishment" sensation Marco Rubio -- who was sure to set the race right in New Hampshire today -- Trump has still topped many polls.
And Trump is up big in the first Michigan survey done after the Iowa caucuses, posting an impressive 14-point lead. Trump scored 35 percent in an eight-way race, while Rubio and Ted Cruz tied for second with 21 percent in the Inside Michigan Politics/Target Insyght survey.
Michigan's primary is just under a month away on March 8. Traditionally, Republicans go for "establishment" candidates here, like Mitt Romney (albeit barely) four years ago, GOP analyst Dennis Darnoi points out.
But this year might be different.
Trump is the ultimate anti-establishment candidate, who crudely talks about banning Muslims from entering the country and erecting a wall to keep Mexican immigrants out. And he's taken verboten economic positions with the GOP donor base, like promising to protect Social Security and Medicare (something that resonates across party lines).
In the poll, the New York developer won almost every geographic area in Michigan, including a third of the crucial metro Detroit vote. But the most interesting number came out of the Flint, Bay City and Saginaw area, where Trump bludgeoned the competition with 50 percent.
That follows the pattern of other outsider candidates fond of stoking racial resentment, like Pat Buchanan and George Wallace, pollster Ed Sarpolus notes. Trump clearly knew what he was doing with his frenzied rally in Birch Run last summer.
As for ideology, Trump won every group: Very conservative, conservative, moderate and yes, liberal. Cruz came close with very conservative voters and Rubio made a run at the moderate vote, but that's as close as it got.
Trump also won three of the four age groups, making him the top choice of voters 35 and older -- which is to say, the vast majority of the likely March 8 Republican electorate.
And here's a number that should make establishment Republicans wake up in a cold sweat: Trump had the most committed voters -- 77 percent. Less than half of Cruz voters and less than a third of Rubio voters said the same.
That indicates that Rubio may be ascendant, but he's yet to solidify his support. So there's still room for another establishment candidate to swoop in, although it won't be clear who that could be until after the Granite State votes today. In the Michigan poll, Jeb Bush, Chris Christie and John Kasich all languished in single digits.
What's the good news for Rubio? Ladies love him -- he came within a whisker of matching Trump's support. So do young voters 18-34, who Rubio won outright. The problem for the freshman Florida U.S. senator is that women and young people don't exactly dominate the GOP primary electorate.
The biggest threat to Trump could be Cruz, the other anti-establishment Republican in the race. He's being underestimated in New Hampshire and has an impressive field operation in Michigan.
So could evangelical voters save Cruz, as they did in Iowa? Surprisingly, no. Right now, evangelicals are actually backing Trump by 10 points in Michigan.
As more states line up to vote, the race will continue to morph. By the time Michiganders go to the polls next month, the GOP primary landscape may look nothing like it does today.
But most pundits insisting that are doing so under the assumption that Donald Trump will finally fade. It's more than past time for us to ask: What if he doesn't?
Susan J. Demas is Publisher and Editor of Inside Michigan Politics, a nationally acclaimed, biweekly political newsletter. Her political columns can be found at SusanJDemas.com. Follow her on Twitter.