(CNN) At around midnight tonight -- and maybe a bit later -- House Democrats will have a considerably firmer grasp than they do right now of their chances of winning the 23 seats the party needs to retake the majority in November.

That's because the massive (and massively important) state of California votes today, with polls closing at 11 p.m. Eastern time. And unlike in election cycles past, where California -- despite its size -- was a competitive wasteland due to a redistricting process in 2011 that sought to firm up incumbents of both parties, there are a surfeit of competitive contests this year.

That may not seem like a huge number. But when you consider that Democrats need to net just 23 seats nationwide to recapture the House majority they lost in the 2010 election, then the importance of California begins to come into much clearer focus. If Democrats can run the table of competitive seats in California this fall, they would be almost halfway to the 23 pickups they need. In a slightly less optimistic scenario for Democrats, a pickup of six seats gets them one-quarter of the way to the majority -- in one state alone!

Which brings me back to today -- and California's very odd "jungle primary" system. Under the 2010 law, which was approved by ballot initiative by California voters eight years ago this month , candidates run on the same ballot. The two top vote-getters -- regardless of party -- advance to the general election. The goal of the jungle primary was to mitigate party polarization -- the theory being that with all the candidates on one ballot, there would be far less incentive for Democrats to run way to the left and Republicans to run way to the right. The ignored moderate voter would be essential again.

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