Two polls of likely voters conducted since last week's primaries show Ernst, a state senator and a veteran who got the support of both the establishment and the tea party, eking out a lead against Rep. Bruce Braley, a Democrat.
Braley, who hopes to keep retiring Sen. Tom Harkin's seat in Democratic hands, had been campaigning well until a tape showed him referring to Iowa Sen. Chuck Grassley as a "farmer from Iowa who never went to law school," a poor choice of words for a state that boasts so many farmers like Grassley -- and Ernst.
A Rasmussen poll released Friday shows Ernst gaining a 1-point lead on Braley, 45 percent to 44, while a Loras College poll gives Ernst a wider advantage, 48 percent over 42 percent.
Election statistics guru Nate Silver warns that Ernst's lead may be somewhat overstated. Silver is skeptical of Rasmussen's track record and Loras College's lack of one, and writes that "candidates sometimes get a temporary bounce from the favorable publicity surrounding a primary win, which then fades." Still, he adjusted his estimate of Braley's chances for victory down to 60 percent, from 75.
And yet, it's not all bad news for Democrats. In the Loras poll, which also finds Republican Gov. Terry Branstad holding a 52-to-38 percent advantage over Democrat Jack Hatch to hold onto his office, Hillary Clinton remains by far the most popular choice in hypothetical presidential match-ups.
The poll finds Clinton holding decisive leads over Republicans Chris Christie (9-point advantage), Mike Huckabee (10 points), Paul Ryan (11 points), Jeb Bush (11 points) and Rand Paul (14 points). And with just 10 to 14 percent of voters saying they're still undecided in those potential races, Clinton's advantage in Iowa remains pretty solid.