Lately, pundits and punters seem bullish on Donald Trump, whose chances of winning the Republican presidential nomination recently inched above 20 percent for the first time at the betting market Betfair. Perhaps the conventional wisdom assumes that the aftermath of the terrorist attacks in Paris will play into Trump’s hands, or that Republicans really might be in disarray. If so, I can see where the case for Trump is coming from, although I’d still say a 20 percent chance is substantially too high.

Quite often, however, the Trump’s-really-got-a-chance! case is rooted almost entirely in polls. If nothing Trump has said so far has harmed his standing with Republicans, the argument goes, why should we expect him to fade later on?

One problem with this is that it’s not enough for Trump to merely avoid fading. Right now, he has 25 to 30 percent of the vote in polls among the roughly 25 percent of Americans who identify as Republican. (That’s something like 6 to 8 percent of the electorate overall, or about the same share of people who think the Apollo moon landings were faked.) As the rest of the field consolidates around him, Trump will need to gain additional support to win the nomination. That might not be easy, since some Trump actions that appeal to a faction of the Republican electorate may alienate the rest of it. Trump’s favorability ratings are middling among Republicans (and awful among the broader electorate).

Read the article “Dear Media, Stop Freaking out About Donald Trump’s Polls” on fivethirtyeight.com.