In many ways, Kansas's primary was a good example of the cycle as a whole. Incumbents like Sen. Pat Roberts (R-KS) struggled badly but still managed to win. Don't be too surprised to see the same phenomenon up and down Tennessee's ballot on Thursday -- but we could see another incumbent (or even two) bite the dust.
-- Rep. Scott DesJarlais (R) in TN-04 is the Volunteer State's most endangered incumbent, but there's still a chance he finds his way to renomination this week, based on three factors. DesJarlais's scandal broke at exactly the right time (nearly two years ago, between the 2012 primary and general) to give it time to fade in people's minds; he's been aggressive about making amends; and outside anti-abortion and other conservative groups haven't gotten involved. That said, much of the Tennessee GOP establishment lined up behind state Sen. Jim Tracy (R), a big help to him despite DesJarlais's "career politician" attacks.
-- As TN-04 has gotten late attention, TN-03 has gone under the radar a bit. But as we've written before, second-term Rep. Chuck Fleischmann (R) has never consolidated the GOP base, winning just 39% in the 2012 GOP primary. Weston Wamp (R) has real flaws, but he's been reasonably well-funded and solid on the trail, and Fleischmann's negative closing campaign hitting Wamp on health care and immigration (including a photoshopped mailer showing Wamp burning a passport) speaks for itself.
-- Then there's the big fish: Sen. Lamar Alexander (R), who has never trailed in polls or faced well-funded attacks this year and, like Sen. Lindsey Graham (R) and others before him, successfully dissuaded any tier-one challengers from testing him. Still, Graham, Roberts, and others have gotten dragged under 60% (or in Roberts's case, 50%) by flawed challengers this year -- though Alexander's in-state favorability has been better than most, too.
Thursday will be the second of three primary days this week, and incumbents have tough battles in all of them.-- Scott Bland