• 40-34 vs. former U.S. Attorney Matt Whitaker (43-34)Braley remains better known than his potential GOP opponents, but his favorability rating has barely budged, from 34-24 last year to 31-25 now. Instead, it's Barack Obama's woes that have put downward pressure on Democrats: He's dropped from a 46-50 job approval score to 40-54. It's a positive sign, though, that Braley's favorables haven't slipped along with the president's. That means voters aren't holding him directly responsible for whatever it is that's caused them to view the White House so dismally, so he can aim for a rebound that's not tied to Obama's fortunes.
• 41-35 vs. state Sen. Joni Ernst (45-33)
• 41-35 vs. former energy company CEO Mark Jacobs (44-32)
• 42-34 vs. radio host Sam Clovis (43-31)
Meanwhile, the GOP primary is still unsettled. Thanks in all likelihood to his early advertising, Jacobs is in the lead with 20, while Ernst takes 13, Whitaker 11, Clovis 8, and a couple of Some Dudes are in low single digits. Democrats would very much like to see the Republican nomination thrown to a convention, but that will only happen if no candidate fails to clear 35 percent. With David Young dropping down to the open IA-03 race and Bob Vander Plaats declining to run for Senate, that scenario is looking less likely.