I have a new column up at CJR exploring why reporters have been mistakenly reporting that Mitt Romney has “momentum” in the presidential race. Here’s how it begins:

On Thursday night, Politico beat a retreat in the great momentum debate of 2012. The site’s Glenn Thrush and Jennifer Epstein opened a big state-of-the-campaign story with this—“In the past 10 days, Mitt Romney’s campaign has gone from Big Mo to Slow Mo”—and went on to note that “an increasing pile of polling data [is] pointing to a race that has stabilized since Barack Obama’s disastrous performance at the Oct. 3rd debate in Denver.” The “Slow Mo” take was a dramatic about-face from a story published three days earlier (not ten!), in which Thrush and his colleague Jonathan Martin contrasted “a surging Romney” with a president who “is currently on the ugly end of Big Mo.”

The new Politico story is also more accurate. The presidential race has been essentially static in the second half of October…

The notion that Romney still had “momentum” weeks after his early October gains in the polls has now been debunked by numerous commentators and academics. And while that pushback is increasingly reflected in campaign-trail accounts, it is worth taking a closer look at why coverage of Romney’s “momentum” went wrong and what it tells us about the weaknesses of campaign journalism.

For more, read the whole thing.