Two Democrats are heading into a runoff in a big political fight for a seat in the state senate, representing the wealthy bedroom communities of the far eastern Bay Area. The contenders are Susan Bonilla, a Concord assemblymember, and Steve Glazer, the mayor of Orinda. The race was held under the rules of California’s new top-two primary, but the role of this new system in producing the outcome is more complicated than it might seem.

Four Democrats and one Republican were on the ballot for this 7th Senate District seat, which became vacant when Democrat Mark DeSaulnier successfully ran for the U.S. House of Representatives. The race boiled down to a pitched battle between the three best-known Democrats: Joan Buchannan, a former Alamo assemblymember; Bonilla; and Glazer. The fourth Democrat received far less attention and the lone Republican actually withdrew from the race and endorsed Glazer (though her name remained on the ballot). At the time of this writing, Glazer has finished first with 33 percent, followed by Bonilla with 25 percent, and Buchannan with 23.

A goal of the new top-two system is to encourage candidates to build centrist cross-party coalitions. All candidates were on the same ballot, and voters could choose any candidate they liked, regardless of party. The top two vote getters, also regardless of party, now advance to a runoff campaign. (Technically, this special election uses a variant of the top two, in which a runoff occurs only if none of the candidates receives at least 50% of the vote. But that did not end up being a factor in this race.)

Steve Glazer fits well in this new system. He has taken a more business-oriented perspective that has put him at odds with many in the party’s pro-union establishment. With the endorsement of the only Republican in the race, he has been empowered to draw Republican voters to his banner. Moreover, the 7th Senate district is in an area with politics only slightly left of center, with more Republican voters than is typical for the Bay Area. As if that weren’t enough, counts of vote-by-mail ballots just before Election Day suggested Republicans were turning out to vote in disproportionate numbers, making them even more critical to the outcome.

However, it is important to emphasize the precise way in which the top two impacts this race. The open ballot—with all candidates listed regardless of party—is not new to special elections such as this one. Special elections have long had an open ballot, so even before the reform the District 7 candidates would have been free to reach across party lines.

The key difference comes now that the first round is over. Under the old special election system, the top vote-getters within each party would advance to a runoff election. Under the new system, the top two candidates advance even if these candidates hail from the same party. Thus, the May match-up between Glazer and Bonilla would have been impossible before the top two.

The irony is that in this particular case, the same-party race has thrown an extra hurdle in the way of the more moderate candidate. Under the old system, Glazer would have advanced to a runoff against a Republican who is no longer in the race. Now he must fight another Democrat to secure his place in the legislature.

But that doesn’t mean the top two has necessarily hurt Glazer’s chances. The same candidates may not have made the same decisions under the old system. Michaela Hertle, the Republican, might not have withdrawn from the race and endorsed a Democrat, because as the only Republican, she would have been guaranteed a spot in the runoff. Glazer might not have run for fear that he would not finish a clear first among all the Democrats. Though one can never be certain about any particular race, there is evidence that the top two has discouraged candidates like Hertle—those who hail from the major party with fewer registrants in a district—and encouraged more candidates from within the district’s dominant party. So while the top two didn’t enable cross-party coalitions in this race, it may have altered the landscape in other ways.

At any rate, there is no doubt that the top two has changed the contest moving forward, since Glazer and Bonilla never would have faced each other in the runoff without it. The ultimate test of the system lies with the outcome of this same-party race, and the political leanings of the person who wins it.