Incumbent Senator Thad Cochran of Mississippi had to pull out all the stops to head off a Tea Party challenger.  Photographer: Justin Sullivan/Getty Images
Incumbent Senator Thad Cochran of Mississippi had to pull out all the stops to head off a Tea Party challenger.  Photographer: Justin Sullivan/Getty Images

First things first: I was dead wrong about the Mississippi Republican Senate runoff. I assumed that an incumbent who finishes second in a primary is toast in the runoff, but Thad Cochran surprised me by fighting hard and winning the nomination yesterday.

At the very least, Cochran's win is important because every individual senator matters. It will be interesting to see how Cochran responds to the scare. Does he shift toward Tea Party rhetoric to consolidate his party position, or does he decide to mainly represent the more moderate coalition that bailed him out? His situation isn't quite comparable to that of Alaska's Lisa Murkowski, but the question of how responsible Cochran will feel to his new (albeit almost certainly temporary) allies among black voters is fascinating.

Beyond this particular senator, the importance of the primary is, as always, mainly a matter of how it is interpreted. Do mainstream conservative Republican senators conclude that the Tea Party is, in fact, beatable? Or do they conclude that even as reliable a conservative as Cochran was almost defeated because he allowed space between himself and the radicals? Either interpretation is plausible.

All politicians are paranoid by nature. The question is what a particular set of politicians will be paranoid about. Objectively, both renomination and re-election remain 90 percent or better propositions. Realistically, very few senators and even fewer members of the House have anything to worry about. But incumbents aren't realistic. They are constantly aware of the threats, potential and future, to staying in office. We can be sure Republicans won't conclude from the Cochran primary and runoff that they're now safe, because politicians never draw that conclusion. So we'll have to leave it to reporters to tell us what lessons Republicans in Congress are drawing from Cochran's close call.

To contact the writer of this article: Jonathan Bernstein at Jbernstein62@bloomberg.net.

To contact the editor responsible for this article: Max Berley at mberley@bloomberg.net.