The rift between "establishment" candidates and their tea party challengers is as much about incumbency this year as ideology.
In the challengers' narrative, a long tenure in Washington brings lassitude and complacency to the conservative cause; those officeholders compromise too much - or spend too much - but don't challenge the D.C. status-quo enough. As the establishment tells it, incumbency brings clout, in that classic "all politics is local" way: it steers spending back home and gets the funds that come more easily to lawmakers with seniority.
We saw this debate in Kentucky - where the establishment prevailed easily - and we were watching it in full force in Mississippi, in what might have been the most compelling fight contrasting these two themes.
That was before the scandal took over.
A few months ago incumbent Sen. Thad Cochran, R-Miss., seemed potentially vulnerable. Cochran, elected in 1978 and seeking a seventh six-year term, seemed to fit that profile of a long-time incumbent in a state where Republicans are staunchly conservative, and he'd drawn the ire of national conservative groups who were angry about debt ceiling and budget deals. They'd hoped to replace him with what they considered a movement conservative, tea party challenger.
Cochran's campaign had stressed all that he's done for the state, hoping that voters would reward him for his efforts including after Hurricane Katrina, especially. The political reality, often, is that spending in principle is usually derided by all sides, but funds that help one's state in times of crisis are often welcomed.
Challenger Chris McDaniel's campaign was invoking the idea that Cochran was past his prime, and McDaniel wasn't new to political campaigns, as a state senator, so many wondered if his campaign could avoid the gaffes and missteps that have hurt tea party insurgents this year and in the last two cycles.
Then a conservative blogger who supports McDaniel was arrested after photographing Cochran's wife, Rose, in her nursing home which many immediately decried as an invasion of privacy. McDaniel has denied ties to the blogger and condemned the action, but the incident has proved inescapable for him so far. Cochran's campaign - though not the senator himself - has made the transgression part of its ads.
That pushback could work heavily in Cochran's favor Tuesday, as it is the kind of incident that can undermine challengers who aren't as well known going in. In general, voters don't usually replace incumbents if there are doubts about the challenger.
The race is not a slam dunk. It's a June primary - in the late spring/early summer, even more so than usual, many voters feel they've more options for things to do other than stand in line to vote. Plus it's a low absentee/mail state, meaning this is a one-shot campaign effort in which only the most committed, more ideological voters could turn out disproportionately, potentially helping McDaniel.
If Cochran hangs on, it's another win for the "establishment" and the first explanation is bound to be the nursing home scandal. What it'll mean is up for debate. Did it distract from or disrupt what might have been a viable anti-incumbent challenge? Or did it prove exactly the point the "establishment" wants to make this year: that it's hard to run campaigns; that challengers have less room for error - real or perceived - with the electorate, even in supposedly anti-incumbent years. And with Senate control on the line, plenty of Republicans think there isn't a lot of room for error.