The big conversation in Sacramento is now about moving up the presidential primary so that California plays a bigger role in selecting a president.

That’s fine. But California’s two political parties shouldn’t go along with the change – unless it’s accompanied by the repeal of the top two system.

The parties would be in the right to push this appeal. Top two has been a failure here. It creates perverse outcomes, discourages people from running, and depresses voting and political participation, especially when two candidates of the same party advance in top two. And it hasn’t produced the greater participation by unaffiliated voters that it’s designed to do.

And the rollout has been embarrassing to the state, and damaging to the credibility of election officials and reformers. They keep insisting that the first round of top two voting is a primary—when, in fact, top two constitutes an elimination of primaries.

The presidential primary question is the perfect chance to make these points – and ditch top two, thus encouraging greater political participation.

Why? Californians’ vote for president is the only vote in which Californians still can participate in real primaries. We get to choose a nominee of our political party. There’s a passion and a connection in such votes that encourages participation. And it’s one reason why we vote more often for president than for many offices.

So the California Democratic and California Republican Parties should respond to legislation to move up the California presidential primaries like this. “We’re heartened by the interest in such party primaries, and the passion people feel for their timing because they matter so much. And we support making California’s more important by advancing them in the calendar. But that’s not enough.

“We want Californians to have the chance to participate in party primaries all across the ballot, and to feel something-close-to-the-same passion for choosing statewide officers and legislators. So we are demanding that, as a condition of moving the primary, that voters be asked in 2018 to reverse the top two system and return to party primaries. Political scientists have found that primaries drive much more participation than non-partisan, jungle ballot first-found voting like we see in top two.”

The parties should insist on connecting the two. If voters don’t restore the party primaries, then the presidential primaries should not move up to March (or earlier) in 2020.

Such a push would not only be in the parties’ self-interest. It would be good for California, and for political participation here.