According to press accounts, Mitt Romney will deliver in Iowa tomorrow “a closing speech framing the economic choice facing voters.” The New York Times reports that the campaign “declined to provide details about what Mr. Romney would say in the speech,” but it's safe to assume that at some point Romney will repeat what has become the central promise of his economic pitch: that as president he will create 12 million new jobs.

Seeing as this is being billed as Romney's final economic pitch to voters, it represents the last big chance for reporters to challenge the Republican on that 12 million jobs assertion and point out that a) that level of job growth is expected regardless of who's president, and b) one of Romney's top economic advisors acknowledged the campaign's math on this issue doesn't add up.

Once again, this is the central economic claim being put forward by team Romney in a campaign that everyone agrees is all about the economy. And the claims undermining it aren't coming from partisan or otherwise interested sources. Both Macroeconomic Advisers and Moody's Analytics project 11.8 million jobs will be created by 2016, and as Moody's Mark Zandi put it: “The forecast is agnostic with regard to who is elected in November.”

On top of that, the math used by the Romney campaign to explain how they'll arrive at 12 million jobs is, in the words of Washington Post fact-checker Glenn Kessler, “mostly made of gossamer.” When Kessler asked the campaign for their numbers on job creation, they sent him three different studies with three different time frames (one uses a 10-year window, another projects an 8-year forecast). Asked to comment, Romney economic advisor Glenn Hubbard told Kessler: “The big point is the 3+7+2 does not make up the 12 million jobs in the first four years (different source of growth and different time period).”

Up to this point some major media outlets have been noticeably unwilling to push back on the “12 million jobs” claim around which the Romney candidacy is built. With Election Day less than a fortnight away and Romney's economic speech slated for tomorrow, it's looking like they have just one more real shot at getting it right.