Six months ago, Gov. Arnold Schwarzenegger seemed unbeatable. Thanks to sky-high approval ratings, international celebrity status and a pliant media, no amount of criticism seemed to stick to him. Today, he is looking more beatable than ever.

A campaign by the teachers, nurses and firefighters unions against his retirement-privatization plan didn’t melt away like previous challenges, and he’s been forced to back down.

This weekend, the California Democratic Party will convene in Los Angeles with an eye toward the 2006 gubernatorial election. A formerly almost-empty field of Democratic hopefuls is now quickly thickening.

If Democrats want to retake the governorship, they must perform five tasks.

First, they must make the case against Schwarzenegger. This is not very hard. People voted for Arnold because he said he had a secret plan to close the budget gap without cutting education. Two years later, he’s raided the voter-mandated education budget twice — after promising not to and then promising it was a one-time thing — and still hasn’t figured out how to close the deficit.

Schwarzenegger ran as a miracle-worker and has governed as a panderer. He’s promised, but he hasn’t produced. When he said he had a plan, he was lying.

Second, Democrats need to reestablish trust with the taxpayer.

Proposition 55, which would have reduced the threshold for passing a budget in the Democratic-controlled state assembly from two-thirds to 55 percent, was recently voted down overwhelmingly by the people. This means that most people voted for Democrats, but most people don’t want to let them write the budget.

No Democrat will be able to govern effectively without public confidence that his proposals are a good use of taxpayer money. This may mean, for the time being, scaling back more ambitious proposals for healthcare, pensions and environmental protection in favor of lowering taxes — because any Democrat who is seen as indifferent to the business climate will get nowhere on these issues anyhow.

Third, they must make a positive case for government. California’s success in the global economy has rested on excellent public investment. Without an educated workforce, we cannot create jobs and remain as the high-tech capital of the world. The infrastructure that makes it cheaper to ship produce from California to Mexico City than from most parts of Mexico is overburdened and decaying, and it will not indefinitely support a growing, export-driven economy. Police using donated surplus old-model radios cannot fight crime. While every dollar spent must be justified to the taxpayer, the Republican plan to slash investment and lower taxes will not produce long-term growth in a global economy.

Fourth, Democrats must embrace political reform. The current system of gerrymandered districts guarantees a legislative majority, but it’s a toothless majority because the voters don’t trust the Democrats to pass laws. Honest competition will stimulate both parties and result in better government, though it will mean cleaning out some of the dead wood in Sacramento. Democrats who oppose Schwarzenegger’s redistricting proposal should come up with a better plan. The rest should get on board.

Fifth, Democrats must be willing to buck organized labor.

Firefighters and police officers deserve a stable pension system, healthcare would improve if there were more nurses and educators trusted with our children’s future should be paid like the professionals they are. But we shouldn’t break the bank with pensions, mandate more nurses-per-patient when there’s already a shortage or protect the jobs of unqualified teachers.

Some of labor’s demands coincide with the public interest, others do not. The first Democrat who acknowledges that will touch off a firestorm, but it is a prerequisite for establishing trust with the taxpayer and proving to the public that government programs are not union giveaways.

The people voted for Arnold because they were sick of the business-as-usual Democrats in Sacramento and because they liked what he was promising. Arnold hasn’t quite broken every promise he made, but he’s come close. With record-low approval ratings, the people are ready to ditch him. But unless the Democrats learn to think outside the mold and accomplish these five tasks — starting this weekend in Los Angeles — they’ll drive the people right back into Arnold’s arms.

Kai Stinchcombe is former president of the Stanford Democrats. If you’re interested in attending the convention in L.A. this weekend, e-mail him at kstinch@stanford.edu.