SACRAMENTO ? On July 11, Gov. Arnold Schwarzenegger scored his biggest victory of the year, signing a budget in which the Democratic-controlled Legislature gave him almost everything he wanted in his effort to cure this debt-plagued state government.

But hard on the heels of that triumph, one of Schwarzenegger’s aides told me this week, “Ka-chunk, ka-chunk. It was like getting run over by the front and rear wheels of a truck.”

On July 13, news reports revealed that just before taking office in 2003, the governor had signed a multimillion-dollar contract with the publisher of two muscle magazines that rely on ads for nutritional supplements – and then vetoed a bill that would have regulated some of those supplements. After 24 hours of brutal editorial condemnation of what another aide called “that $8 million mistake,” Schwarzenegger gave up that income and scrapped another multimillion-dollar deal to promote a body-building festival in Columbus, Ohio.

Then a California court threw one of Schwarzenegger’s key initiatives off the ballot in the November special election he had ordered – a measure aimed at transferring the power to draw legislative and congressional district lines from the Legislature to a panel of three retired judges. Those the governor had entrusted with qualifying the initiative had mistakenly submitted a title and description to the attorney general slightly different from the language on the petition forms signed by voters – a big enough discrepancy for the judge to invalidate the petitions.

An appeals court has stayed that order, pending a review, but suddenly, a Republican who seemingly had brought an aura of invincibility with him from his Hollywood strongman days appeared to be stumbling and gasping for air.

Last weekend, California papers quoted Mike Murphy, Schwarzenegger’s political consultant, as speculating that he might try to call off the special election – only to have that message countermanded by the governor’s official spokesman.

So, at the moment, both sides are preparing for a showdown on the November ballot, with Schwarzenegger and his business allies focused on a budget reform that would significantly limit the Legislature’s ability to put windfall revenues – such as those generated by the 1990s’ dot-com “bubble” – into continuing programs and at the same time expand the governor’s power to cut spending when revenues slump.

Arrayed against him is a coalition led by public employee unions and their private-sector allies. They have mounted an expensive ad campaign that has contributed to a severe slump in Schwarzenegger’s poll ratings. The Public Policy Institute’s July poll put his job approval at 41 percent among likely voters, down 22 points from January.

Polling on the budget proposal indicates it, too, faces an uphill battle, because it would trim education spending. Defeat on that issue would send Schwarzenegger into the last year of his term on a downward slide.

That explains why one of those directly involved in managing his initiative campaign said, “We’re preparing for war, but we’re praying for peace,” a last-minute compromise with the Legislature that would make it possible to cancel the special election. But the odds are against any such deal; a senior Schwarzenegger strategist gives it only one chance in five. The special election ballot also includes two issues of particular importance to conservatives. One would require notification of parents before a minor could receive an abortion. The other would force public-sector unions to get annual approval from each of their members to use their dues for political purposes. The GOP hard core wants to vote this year on those issues.

So far, Schwarzenegger has not embraced the union dues measure, and his continued neutrality could also be part of the price Democrats exact in a deal. The unions defeated a similar but broader measure in 1998, and if they think they can do so again in the special election, they’d prefer to have it out of the way before next year’s campaigns begin. They can’t, however, be sure of victory.

Even in his current weakened condition, Schwarzenegger is in a statistical tie against two unexceptional Democratic challengers for the 2006 election. Union leaders concede that he could – like predecessors Pete Wilson and Gray Davis – win another term despite weak personal ratings.

What he cannot do, most observers agree, is regain the status he once enjoyed as a popular hero whose appeal transcends normal partisan and ideological lines. His rhetorical attacks on teachers, nurses and other political foes have polarized voters. The gamble he is taking with a special election is a big one – and the Terminator is looking wobbly as he approaches it.