Congresswoman Loretta Sanchez’s best chance in the U.S. Senate race – the theory goes – is to grab the second spot in the June first round of the top two contest, and then rally against the frontrunner, Attorney General Kamala Harris, in the November runoff.

This Sanchez path to victory looked viable when there were three Republicans in the race, thus dividing that vote so that even the top GOP finisher would have less votes than Sanchez. But the path doesn’t look nearly so good after one of the three Republicans, Assemblyman Rocky Chavez, quit the race.

That leaves two Republicans – Tom Del Beccaro and Duf Sundheim, both little-known former GOP chairs – to divide up the vote. And Sanchez probably needs that race to be very close to be the second choice if she’s second. A U.S. Senate race under top two is a California novelty, but in legislative districts that resemble the state’s divide between Democrats and Republicans, top two usually produces one Democrat and one Republican.

So Chavez’s departure should light a fire under Sanchez, whose campaign has been low-profile, and under Harris. The only sure way to win in November is to best the other in the top two. Look for more attacks and more visibility now – Chavez’s departure should mark the beginning of the race.

The June contest will become even more important if one of the two Republicans drops out, which seems unlikely at this point, but hardly inconceivable.

And if you’re one of those who is bothered by the idea that the machinations of Republicans could so greatly influence the choice of Democrats in selecting a U.S. Senate candidate, welcome to the perversions and horrors of the top two.

Top two is a system that boosts kingmakers, donors and extremists, while reducing voter choice and participation. Indeed, Democrats are probably being denied other choices for Senate – but, in a top two, system, having too many candidates is a risk for a party.

One wonders how long before we see a strange result in an election – say two Republicans advancing in a multi-candidate Democratic race – and a movement to end this failed experiment.