In the 2018 election for governor of California, surprised voters might well find only two Democrats to choose from in the general election – which would be a historical first in a governor’s race. Why? Because the sorely depleted California Republican Party may not be able to come up with a candidate who can make the runoff in the state’s top-two primary process.

Since the voter-approved top-two primary went into effect in 2012, one governor’s race and two U.S. Senate races have been put through that sieve. The raw numbers tell a story that should not be comforting for even the most avid GOP cheerleader. Let’s walk through the instructive results.

The first statewide race run under the top-two scheme was Sen. Dianne Feinstein’s 2012 re-election. A larger-than-life figure who is always a top vote-getter, Feinstein still drew five Democratic primary opponents, although none of any real note. But on the Republican side, an odds-and-ends drawer of 14 candidates filed, including an 81-year-old failed candidate for state treasurer and a birther gadfly. Ultimately, Feinstein won 49.3 percent of the primary vote, and moved into a runoff with Republican Elizabeth Emken, an unknown autism activist with the next-highest vote total – at 12.6 percent.

Suppose a well-known Democrat had decided Feinstein had served long enough after 20 years, and filed against her in the open primary – say, Lt. Gov. Gavin Newsom, or state Treasurer Bill Lockyer, a well-known former two-term attorney general. If they had run a viable campaign, can anyone imagine that either would not have received more than Emken’s 12.6 percent, and moved on to a Democrat-on-Democrat runoff that fall?

Feinstein probably still would have prevailed, but she has never been the darling of the Democratic base, and as Bernie Sanders showed, an insurgent can make substantial headway among progressive Democrats even against a formidable front-runner.

Which brings me to the 2016 race to replace the retiring Barbara Boxer in the U.S. Senate. Again, this was a top-two primary. On the Democratic side, Attorney General Kamala Harris was joined by longtime Democratic Rep. Loretta Sanchez of Orange County. The GOP side again featured a cast of thousands. Although the party hierarchy clearly preferred former state Republican Party Chair Duf Sundheim, they were again incapable of keeping the field clear, and 11 more GOP candidates filed, including yet another past GOP chair.

The better-funded Harris, who had already been elected statewide twice, and had a dependable base in the high-turnout Bay Area, finished first in the primary with 40.2 percent of the vote. Sanchez, who struggled to gain traction and trailed from the very beginning, received only 19 percent.

But that still qualified her for second place, and she moved on to the general election runoff (which she lost). The top vote-getting GOP candidate, the party-preferred Sundheim, finished with a paltry 7.8 percent, while the other Republicans split another 20.9 percent of the primary vote.

The 2014 governor’s race is also instructive. The then-76-year-old Jerry Brown was running for re-election for governor – for the second time in his long career – and drew only one Democratic opponent, an unknown guy born in Nigeria who raised only a little more than $1,000. On the Republican side, the leading candidate was state Assemblyman Tim Donnelly, an immigrant-bashing Minuteman.

With no viable Democrat other than Brown on the ballot, state GOP poohbahs panicked over the possibility of Donnelly finishing second and further tarnishing the party brand among immigrants and minority voters. So they recruited Neel Kashkari, an obscure former official in the George W. Bush Treasury Department. After infusing his own money into the campaign, Kashkari finished a distant second to Brown’s 54 percent, with 19.4 percent of the primary vote, while Donnelly came in third at 14.8 percent. Kashkari was demolished in the runoff 60-40 by Brown.

As with the 2012 Feinstein primary, suppose Brown had drawn a real Democratic challenger, say Los Angeles Mayor Antonio Villaraigosa, or state Controller John Chiang, both of whom are running for governor in 2018. Would Kashkari still have finished second, or would that runoff have been Democrat-on-Democrat runoff like the 2016 Senate race? The numbers cannot be heartening for the state Republican Party.

So far, no well-known Republican candidates are running for governor in 2018. There is a San Diego-based multimillionaire (we know how self-funding, first-time rich candidates have fared; see, Whitman, Meg), a right-wing Assembly member from Orange County and a former Assembly member from L.A. County who served one term before being bounced by voters. Hope springs eternal in Republican breasts that GOP Mayor Kevin Faulconer of San Diego will run, but he has done everything but hire a skywriter to disclaim his interest.

At the end of the day, can a political party that is now down to an all-time low of only 25.9 percent of California registered voters even get a Republican candidate into the gubernatorial runoff in 2018? Oh, and whose presidential nominee lost the state in 2016 with only 31.5 percent of the vote – the lowest percentage of any GOP nominee since Alf Landon in 1936 – and whose approval rating in the Golden State is 27 percent? Time will tell, but in the meantime, don’t bet on it.