Donald Trump started today with the bright sheen of the frontrunner in Iowa. Now, he's struggling to get a second-place finish. Obviously, Iowa isn't everything (just ask Rick Santorum), but the sharp divergence between Trump's poll numbers a few days ago and his performance in the caucuses tonight is nevertheless striking.
So what are some possible reasons why Trump has fallen?
The conservative media assault has left a mark: Over the past couple weeks, many conservative organs--including National Review and The Weekly Standard--have taken a howitzer to Trump. In the aftermath of this assault, Trump's numbers have dropped.
So has the battle with Ted Cruz: Cruz and Trump entered a titanic struggle in the weeks leading up to the caucuses. This battle drove up Trump's negatives and drew fire from conservative talk radio. While Cruz and Trump tangled, Rubio kept his distance and was able to pick up voters.
The ground game matters: Ted Cruz's ground game was reputed to be very formidable--and it looks like it lived up to its reputation. Cruz and Rubio both tapped into networks of Iowa activists. Retail politics still counts a lot.
The celebrity brand is a double-edged sword: Trump's brand as a pugnacious celebrity has helped draw attention to his campaign. However, in the voting booth, that same branding might alienate some on-the-fence voters.