Today is election day — one of the biggest ones of the year. The big headline is Scott Walker’s attempt to avoid being recalled in Wisconsin. But there’s a lot more, and much of it is quite important. Remember, primary elections aren’t just about candidates; they’re fights over who really runs a political party. If you care about politics, that’s a top concern.

House primaries in California, New Jersey, and New Mexico: The headlines in these are the Member-Member races caused by redistricting. In California Howard Berman and Brad Sherman were thrown into the same district. However, thanks to the new “top two” primary structure there, the likely result tomorrow will put them both on the November ballot, so the primary is only a preview. But they are both high profile legislators, and one will ultimately have to leave Congress.

However, in New Jersey, either Bill Pascrell or Steve Rothman will be defeated. That race is worth watching because it has been reported as splitting Bill Clinton (endorsing Pascrell) and Barack Obama (perceived to be leaning to Rothman). Both of these are solid Democratic districts, so in both cases, these races will help determine who’s in the House next year.

Senate primaries in New Mexico, New Jersey, California, and Montana: The Senate primaries today are important for what they tell us about the overall situation this year: Republicans have clear opportunities, but they may not take full advantage of them. In Montana, the GOP has recruited a strong challenger to Senator Jon Tester — Denny Rehberg — and he will win his primary easily. In New Mexico, the GOP will field a strong candidate for Senate — Heather Wilson — and today Dems will vote in a primary and choose between two viable candidates to take her on in a race which could help determine control of the Senate.

But in New Jersey, the GOP seems to have failed to find a strong challenger to seemingly vunlerable incumbent Bob Menendez, and today Republicans will choose from among a group of apparently weak contenders. And California is a Republican fiasco. Not only is there no strong candidate to force Senator Dianne Feinstein to work up a sweat this time around, but it’s possible (under the new California primary law) that the Republicans won’t even manage to get a candidate on the November ballot.

Or if they do, it could be birther queen Orly Taitz, which would be an impressive embarrassment both to the party and to Mitt Romney.

Remember: individual Senators matter a lot in Congress, and today’s primaries will go some way towards determining the next batch of freshman Senators — and who controls the Senate next year. In the battle for control of the House, every potentially close race counts — and candidates typically matter a great deal. So while the headlines tonight will be about Scott Walker, and rightly so, keep an eye on these other races. A few years from now, odds are that one or more of them will have turned out to be the real story today.