California's voters dealt the state's major parties somewhat of a blow two years ago with this passage of Proposition 14, which created a Louisiana-style top-two primary. (A little bit of background here.) The top-two primary means that for any given office, voters may choose from candidates from any party. Voters in the 47th congressional district, for example, are presented with a list of four Democrats and four Republicans. (You can see some others here.) The top-two vote getters in the primary, which will be held on June 5th, will go to a November general election.
The probable outcome in the safer districts is that you'll end up with two candidates of the same party running against each other. An Orange County district may end up with a moderate Republican facing off against a conservative Republican; a San Francisco district will likely end up with two Democrats for November. This is a situation which may favor more moderate candidates, who stand to win independents and minority party voters in the fall. Indeed, some moderate Republican groups in California are seeing this as an opportunity to win some representation in the statehouse, and some Republican candidates who haven't signed an anti-tax pledge may actually have a shot this year. (Although the Washington Post is reporting that this may be more of a nationwide trend.)
These possibilities are unnerving to party leaders, of course, and they have come up with an interesting solution. Both parties have endorsed candidates in many of the congressional and state legislative races, hoping to signal to loyal partisan voters just who the true Republican or Democrat is. Now, as it happens, this endorsement information does show up in the voter pamphlet sent out by the Secretary of State, but not on the same page as the candidate listings. That is to say, any voter interested in getting a party's advice on a race will have to turn some pages and do a bit of extra reading. The signal really isn't in their faces. But through these endorsements, party leaders are hoping to get around the top-two structure and produce something more like the closed primary that the state has used for years.
It'll be interesting to see just how effective this is. I should point out, though, that a fair amount of evidence suggests that opening up a primary does little or nothing to moderate politicians. A paper I did with Eric McGhee, Nolan McCarty, Boris Shor, and Steve Rogers found just about no consistent effect of primary rules on the partisanship of elected officials. Then again, we don't have too many examples of states using a top-two system. Louisiana has such a system, and its state legislature is notably depolarized. Perhaps this system could have such an effect on California, but I'd say the odds are low. Party leaders are quite adept at working around such challenges. We'll know more soon.