Practice begun in 2012 under ex-governor Schwarzenegger could see two Republicans advance to general election

As Californians cast their ballots in Tuesday’s primary election, voters can select any candidate among the long list of gubernatorial hopefuls, regardless of which party they have registered under.

The system was put in place under former governor Arnold Schwarzenegger, who supported the open primary, or “jungle primary”, as a way to create more competition in races that Democrats won year after year. Schwarzenegger, who left office in 2011, was the last Republican elected to statewide office in California.

In a crowded race like this year’s gubernatorial primary, the system could cause some unexpected results – such as the possibility that emerged earlier this year of two Republicans advancing to the general election in deep blue California.

That situation now appears unlikely, but the possibility has prompted some Democrats to push to overhaul the way the state votes.

How does an open primary work?

Before the reforms, each political party chose a nominee to advance to the general election, with only the party’s registered voters participating in the primary election.

In 2010, California voters approved the Schwarzenegger-backed ballot measure to change that traditional partisan primary.

The new system folded the previously separate primaries for Democrats, Republicans and third parties into a single race. That means all candidates for a particular office run on the same ballot.

The two candidates who secure the most votes face off in the general, regardless of their party affiliation. In California, that often means a general election can pit two Democrats against each other.

The logic behind the top two, according to proponents, is that candidates will feel compelled to consider the needs of voters outside their political faction, as the primary is open to all registered voters. Nebraska and Washington use similar processes.

Abel Maldonado, a self-proclaimed “pragmatic Republican” who spearheaded the California effort, told the Atlantic in 2015 that with the then-new open primary, aspiring elected officials “have to work for the taxpayers”.

Why are some Democrats calling to change the system?

While the party has a stronghold in much of California, there has been recurring fear that having multiple Democratic contenders in one race will dilute the party vote and inadvertently pave a path for two Republicans to compete in the general election.

Those concerns resurfaced in this year’s governor race after two Republicans, the conservative pundit Steve Hilton and Riverside county sheriff, Chad Bianco, surged to the top of early polls.

Conversely, some Republicans have been worried about being excluded from general election ballots in the reliably Democratic state.

The likelihood of two Republicans making the general election has since subsided, in part because of two major events that shook up the race.

In April, Eric Swalwell, a Democratic frontrunner, suspended his campaign amid a spate of sexual assault allegations. (Swalwell has denied the claims.) The implosion of Swalwell’s campaign opened up an opportunity for Xavier Becerra, the former US secretary of health and human services, to surge to the front of the crowded pack of Democrats in the race.

Also in April, Donald Trump endorsed Hilton, a move that appeared to coalesce Republican voters around the British-born commentator.

The latest polls ahead of Tuesday’s primary show Hilton polling closely against Becerra and Tom Steyer, the billionaire Democratic candidate.

What happens next?

Steven Maviglio, a Democratic political strategist, has pushed for a 2028 ballot measure to repeal the top-two primary system regardless of what happens in 2026.

“It’s a failed experiment that even the remote possibility of a Democrat having to choose between two Trump Republicans in November is enough to scare the bejesus out of anyone,” Maviglio told the San Francisco Chronicle in mid-May. He filed a proposal with state officials this month, requesting a return to partisan elections.

That initiative is stages away from being on a ballot. The California attorney general has to issue a summary and title for the proposal and a legislative analyst will assess the cost of the idea, Maviglio said over email. A certain number of registered voters must sign on for it to advance in the process.

Rusty Hicks, chair of the state’s Democratic party, echoed the call for reform in an interview with the Guardian earlier this year. “The current system we have does not work,” he said, referring to the prospect of a Republican gubernatorial bid being fueled by a cluttered slate of Democrats. “It needs to be revised or repealed.”