When you get beyond the excitement of contemplating something that's never happened before, something that might redefine the state's political landscape, what you end up with is historical data and harsh electoral realities that suggest partisan results for 2016's U.S. Senate race that will look a lot like those in days gone by.
And it all starts with the key to any election: turnout.
Does Anyone Vote In Primaries Anymore?
Over the course of the past 30 years, there's been a generally downward trend for voter participation in California's primary elections. While 2014 saw a new low -- 25 percent of registered voters -- there hasn't been a June statewide primary that's broken the 50 percent turnout threshold since 1982.
The only exception to that trend was when California, desperate for a meaningful role in the presidential races, moved its primary to either February or March (and sometimes split the presidential and state office primaries into separate elections). Twice, in 2000 and again in 2008, these early primaries actually boosted turnout. But it was mounting criticism -- both the cost of these elections and the fact that other states still had more presidential clout -- that doomed the early primary. In 2011, state lawmakers rewrote the rules and moved everything back to a single primary in June.
All of this is a long way of saying that history suggests a strong chance of tepid turnout on June 7, 2016.
The presidential race will almost certainly have wrapped up by then; and even if it hasn't, there might be better odds of a nomination fight between Republicans (like in 2012) rather than Democrats. If that's true, then the June 2016 primary would almost certainly see low Democratic turnout relative to the party's dominance among the ranks of registered voters.
That leads to another part of the story: Republicans are much more reliable voters in primary elections. As political data guru Mitchell pointed out in an email on Wednesday, the state's 15-point registration gap between Democrats and Republicans shrunk to just 9 points in actual voting in June 2014.
2016, he thinks, will again "see larger-than-registration turnout by Republicans."
So either a big field of Democrats vying for the seat being vacated by U.S. Sen. Barbara Boxer (D-California) ... or even just two or three heavyweights ... could result in a major dilution of what would already be decreased Democratic dominance.
Crossover Voters? Not By Republicans, It Seems
But what about Republican voters? Given that the top-two primary allows anyone to vote for any candidate, might they be tempted to play in the sandbox of a potential Democratic slugfest for the Senate in June 2016?
Probably not, said Eric McGhee, who studies voting and election issues at the nonpartisan Public Policy Institute of California.
"Republican voters tend to stick by their party everywhere," said McGhee. "Democratic voters often cross party lines to support Republican candidates, especially in places like the Central Valley."
McGhee's take on the top-two (or "jungle") primary, which has only been in play for two election cycles, is that it hasn't shifted the behavior of party loyalists.
"Party registration predicts outcomes almost as well under the top two as it did under the old primary system," said McGhee. "I'm not saying there aren't voters who take advantage of the top-two system -- just that there aren't enough such voters to change our basic expectations."
Last year, we saw polls showing a small but notable number of Republicans in late polling saying they would vote for Gov. Jerry Brown over GOP challenger Neel Kashkari. There may have also been GOP voting for U.S. Sen. Dianne Feinstein (D-California) in 2012, when she received more votes in the fall election than did President Barack Obama.
But those were races featuring an incumbent -- not open seats like the 2016 Senate contest, said PPIC's McGhee.
"There won't be an incumbent on the ballot," said McGhee. "That's a huge difference, and one that makes party-line voting much more likely."
2014: The First Real Test of Top-Two Primary
Better to look, say observers, at what happened in June 2014 -- the first real test of the top-two primary in statewide elections -- and its impact on two open seats: the races for state controller and secretary of state.
In the secretary of state's race, 51 percent of the votes were cast for a Democrat but were spread out over four candidates. Republicans received 36 percent of the votes cast -- 8 percentage points higher than their statewide registration.
In the state controller's race, even more GOP power was exerted: a whopping 46 percent of the votes cast in the race were for one of the two Republicans, 18 percentage points above the party's statewide registration. Democrats split their votes so severely between two well-known candidates that the second (and unknown) Republican almost toppled both of them.
Might Primary Elections Permanently Be Small Potatoes?
There's also not much out there to suggest that June statewide primaries are going to stop being ho-hum elections anytime soon.
For starters, the state's major political parties have done a pretty good job of avoiding the kind of public intraparty spats that would generate a lot of intensity the way, say, the 2008 presidential contest did. The California Democratic Party has an endorsement process that can help galvanize support behind one Democrat over others (Republicans are less likely to endorse one candidate over another).
And already, some Dems are privately hoping there's a way to rally behind either a single candidate -- like the already-running Attorney General Kamala Harris -- or avoid a battle of big names that could include San Francisco billionaire environmentalist Tom Steyer or former Los Angeles Mayor Antonio Villaraigosa. Even if there's a Democratic cage fight, it's hard to envision GOP voters breaking ranks for one of them.
And then there's the fact that June's statewide ballot will be short -- as in, no big ballot measures. Actually, pretty much no ballot measures.
Little noticed at the time, but now a big factor in California elections, was the 2011 law signed by Gov. Jerry Brown to move all initiative and referendum fights to fall ballots. Whether it was good government or a clever political play is now irrelevant. What it means is that a high-profile ballot measure campaign -- the only thing other than an intense candidate contest that seems to draw out voters -- won't be a way to boost turnout among Democrats or any other political voting bloc.
And finally, it may have been a different era altogether, but consider this: The last time a primary election in California turned out more than two-thirds of registered voters was June 6, 1978.
