This race reminds me of Virginia 2013. I'm sure Iowans would like more choices than potentially-impeachment-voting Ernst and chicken-suing Braley, but they'll have to pick a lesser evil between the two of them. My gut says Ernst is ahead now, since Braley's mini-scandal broke more recently than hers, but Iowa is a Tilt D state and Ernst is a B-list candidate, so I do think Braley is still favored overall.
Give the race more time to cook to make a projection. That's my book. Don't forget Branstad is popular, so he might help Ernst out.
