In the dead of night last week, Sen. Abel Maldonado managed to pull off an incredible coup: getting a two thirds vote to place the open primary on the June 2010 ballot in exchange for his vote on the budget. In the light of day partisans of all stripes are howling their heads off, but it too late. The measure is on the ballot.

A little history. In 1996 voters enacted an open primary constitutional amendment that allowed all voters to vote for all candidates for each partisan office in the primary. The parties hated this, and sued in federal court. In 2000, the US Supreme Court declared the California open primary unconstitutional as a violation of “parties associational rights” (whatever they are) because Republicans could help choose the Democratic nominee for office, and vice versa.

But the court left a loophole. If you did not have party nominees, you could have a “blanket” open primary. The state of Washington had long had the blanket primary, and to meet the Supreme Court mandate, Washington in 2004 enacted a blanket primary, top-two runoff with no party nominees. (Candidates can show that they “prefer” a party). This new law was upheld by the US Supreme Court in 2007 and Washington used it for the first time in 2008.

That is what Maldonado’s “Top Two Candidates Open Primary Act” seeks to accomplish for California. All candidates for statewide office, congress and the legislature would appear on the same ballot, and all voters, including independents, could vote for whomever they choose. Then the top two candidates would run off in November. This is how we elect local government and the superintendent of schools under current law. Candidates will not be nominees but can show their party preference.

Can this pass? There are three reasons why it can.

The major opponents are parties and incumbent legislators who like the closed primary where they campaign just to their partisan true believers. But Californians are de-aligning from the parties; independent registration goes up a point each election cycle and includes a fifth of the voters today. Partisan registration is at an all time low. And the legislature’s popularity is somewhere south of Jack the Ripper. Maldonado could not ask for a better bunch of opponents.

Secondly, on arcane measures like this voters look to the ballot label and title & summary they see in their election materials. The legislature has enacted the ballot label and title & summary for this measure, and they stress the additional choice voters will have and increased participation in the process. This is what voters want. They will see that this measure does what they want done.

Third, this measure is on the June primary ballot, voters will see it after they have voted for the partisan offices. The proponents can ask them if they wanted more choices than they had. So the measure can be tied to experience voters have just gone through. California voters always want more choices.

But passing this measure still will not be easy. The Republican right hates it but Republicans are no longer relevant to the political process. Democrats can force through any majority vote bill they want. Also, the GOP may lose its ability to stop tax increases and bad budgets because labor and the Democrats plan to qualify an initiative for next year authorizing a majority vote budget and majority vote tax increases.

The only way for Republicans to be relevant in the legislature is to elect more pro-business Democrats that can join with Republicans to stop big spending bills. Labor and liberal Democrats well understand this reality, and already Maldonado and his open primary are under severe attack from the hard left. The Democratic blog “Calitics.” warns that this measure could populate the legislature with a house full of Joe Liebermans.

They are right. In each election this decade the business political action committee, JobsPac, has poured millions into primary elections trying to elect centrist and pro-business Democrats. They have been singularly unsuccessful because they are trying to do the impossible: nominate moderates in a closed Democratic primary dominated by liberal activists and public employee unions.

But the open primary can change that. Now independents and Republicans will be able to participate in the election in safe Democratic districts. The Democratic legislators will have to listen to all their voters, not just the unions. No more will they be able to tell business lobbyists, “Gee I’d love to be with you but I just can’t cross labor.”

Labor will join with the Democratic establishment – the same people who tried to pass a crooked term limits initiative and kill redistricting reform – to trick the voters into reducing their choice at the ballot because it endangers the left wing stranglehold on the legislature.

Will business step up to the plate and make sure the campaign to pass the open primary is properly funded? We will see if Maldonado’s midnight move was a fireball in the night or just a bad dream.