The GOP is gaining in the polls and on the airwaves. Coincidence?

Money is starting to flow more freely into contested Senate races for TV ads on behalf of Republican candidates, according to data from the Wesleyan Media Project. In Iowa alone, where Republican Joni Ernst leads in the race to replace retiring Sen. Tom Harkin (D), the two sides bought over 11,000 ads for the two weeks from Sept. 12-25 -- 57 percent of which were for Ernst.

Why does that matter? Because ad dollars translate into votes.

In fact, in seven of the eight most tightly contested races, the advantage...