That brings us to the second point, which is that Carson’s particular struggle is that he filled a similar niche to Trump: The outsider who doesn’t come in with any political baggage, boasts of his success in his own profession, and appeals to voters attracted to a shoot-from-the-hip style. You can watch Trump suck up all the oxygen (and then some) that was feeding Carson’s success on Google Trends. Remember, before Trump entered the race and started making bizarre statements about Mexicans and John McCain, Carson was saying Obamacare was the worst thing since slavery and accusing the AP History curriculum of preparing teens to join ISIS. Both men share the basic partisan incoherence of non-politicians, taking positions associated with both parties—no vice, to be sure, though displeasing to staunch conservatives. Trump took Carson’s favorite campaign tricks and turned them up to 11.

Meanwhile, Carson’s fundraising—heavily focused on small contributions and direct mail—is faltering, while he continues to burn through the cash he has already raised.

The success of these two candidates shows a real hunger for people who aren’t traditional politicians. (Americans say they’re sick of career politicians, but when they express that preference by backing outsiders, pundits are suddenly confused!) But these outsider candidates seldom get anywhere near the nomination, and the Carson-Trump swap suggests there might not be room for two of them at any given moment.

What has Carson been up to? He criticized Planned Parenthood, but stumbled typographically in doing so. He's been raising a lot of money in Iowa. He expressed support for Obamacare’s practice of banning insurers from refusing patients with pre-existing conditions. And he defended none other then Donald Trump after Trump made light of McCain’s time as a prisoner of war. Maybe sticking up for the Donald wasn’t a great strategic move!

Or maybe Carson will rise again (after Trump burns out, perhaps). It wasn’t until September of 2011 that the 2012 election cycle produced the strange string of briefly popular Mitt Romney alternatives who grabbed headlines, then disintegrated: first Rick Perry, then Herman Cain, Newt Gingrich, and finally Rick Santorum. Since it remains hard to imagine Trump riding this gravy train all the way to the nomination, his rivals can console themselves with the thought that he may just be the first of a string of ephemeral candidates to surge to the lead. Republican insiders, though, may want to invest in some Alka-Seltzer.