Today is primary election day in eight states across the land (including my own). The most media attention will be paid to the Mississippi Republican Senate primary, where the incumbent, Senator Thad Cochran, may be in trouble from a Tea Party challenger. So while the storyline a few weeks ago was "Establishment Republicans win big over Tea Party," the storyline tomorrow may be "Tea Party strikes back!"

As I wrote back then, it is getting tougher and tougher to accurately state the power of the Tea Party movement. Yes, some of their pet candidates got defeated in primary elections, but on the other hand they have successfully driven the entire Republican Party far to the right. The case can be made either way, really. And that doesn't even get into debating the accuracy of the "Tea Party" label, for each individual candidate.

Nate Silver wrote a fascinating article recently, in which he argues that the label "Tea Party" has outlived its usefulness altogether. He writes:

Perhaps it's time to discourage the use of "tea party." Or, at the very least, not to capitalize it as The New York Times and some other media organizations do. "Tea Party" looks better aesthetically than "tea party," but triggers associations with a proper noun and risks misinforming the reader by implying that the tea party has a much more formal organizational infrastructure than it really does.

As I said, he makes an interesting case, but for the nonce we're going to go ahead and keep using it (and capitalizing it) here in these pages. We can always revisit the issue later, if need be.

The Tea Party has always been nebulous, from the very beginning. The movement has grown into three basic arenas from its origins as a grassroots protest movement (in its very earliest days). There is still a grassroots aspect to the Tea Party, with lots of little local groups in various states who organize for their own purposes. The second area was more AstroTurf than grassroots, as some big-money Republican operatives looked to co-opt (and cash in) on the movement, creating big national organizations like the "Tea Party Express" and others. The third area is the one where Tea Partiers truly made their mark, in politicians who took up the mantle and used it as their own. There's some fuzziness in determining who can accurately be called a "Tea Partier" (there always was, in fact), but there are at least 50-60 House seats and a handful of Senate seats (Ted Cruz, for instance) who proudly call themselves Tea Partiers. They have worked within the system to form a bloc of votes, which is where their real power (especially over the Republican Party as a whole) lies.

There is, however, a sort of shorthand used by the media (and some politicians on both sides of the aisle) -- that of labelling any Republican candidate who slips into looney-tunes territory with some idiotic comment or another a "Tea Party candidate." I've heard debates about whether people like Todd Akin or Richard Mourdock truly qualified as Tea Partiers -- but most of these debates took place after they both spectacularly lost their races. Not all lunatics in Republican clothing are Tea Partiers, to put this another way. Some Tea Partiers can get quite bitter when talking about political opportunists who grab the Tea Party banner for their own advancement, but who aren't true Tea Partiers (at least, according to other Tea Partiers). I've never yet heard the term "TPINO" used, but that's probably because it doesn't roll off the tongue as well as the more-common DINO and RINO.

Realizing that the term Tea Partier isn't a hard and fast one, and mistakes can be made, we still feel comfortable drawing attention to a few of the races which will be decided today. Thad Cochran is going to get most of the attention, but there's a candidate in Iowa who may win the chance to run against Democrat Bruce Braley this fall who probably qualifies as a Tea Partier, at least under the loosest of definitions. She's already run an ad featuring the castration of a hog, as well as one with her at a shooting range, if that's any indication. In California, the Republican in the lead for the chance to lose to Jerry Brown this fall got caught trying to bring a loaded gun through an airport. These are not the fringe candidates, mind you, these are the front-runners in each of these races, on the Republican side. The Huffington Post has a great rundown of all the important races held today, if you'd like more details about these characters.

If any of these candidates win, they'll likely be referred to as Tea Partiers. Which will, as I mentioned, likely drive the storyline of "Tea Party strikes back!" in tomorrow's news. Democrats would (obviously) love to see the Tea Party do well tonight, because it could make November a lot easier for them. If the Tea Party candidate knocks off Thad Cochran, it improves the slim chance a Democrat could steal his Senate seat. In Iowa, Bruce Braley made a stupid comment earlier denigrating farmers (not wise, in Iowa), but his chances would look a lot better if he got the most extreme candidate to run against. In either case, all it would take is one wayward comment about rape or abortion or one spectacularly bad television ad (such as "I am not a witch") to give Democrats a fighting chance to both hold Iowa and perhaps pick up Mississippi (as bizarre as that last concept may sound).

I don't think the Tea Party is any more influential this election cycle as in the last two, myself. But I don't think their influence has slipped much, either. The voters of many states have decided that electability is more important than fervent beliefs, but as we may see tonight, this is not true everywhere. But then, it wasn't true in 2010 or 2012 either -- only a handful of fringe candidates made it through in each of those years too. So I'm going to try to refrain from drawing sweeping conclusions about the Tea Party's strength within the Republican Party, no matter what the returns say tonight. I think in most of these races it comes down to the individual candidates themselves rather than a nationwide movement, so I'll try to continue to focus on the individual candidates rather than trying to see any bigger picture, at least for the time being.

-- Chris Weigant

Follow Chris on Twitter: @ChrisWeigant