SACRAMENTO, Calif. (AP) – It may be that Gov. Arnold Schwarzenegger and the state’s Democrats have given up, for now, working out their differences in the Legislature over a series of constitutional amendments to overhaul state government and politics.

Instead of arriving here Friday to promote the Republican governor’s plans at the GOP’s spring convention, state Republican Party delegates will gird for what they expect will be an unprecedented special election this fall.

“California Republicans are on the offensive,” said Ron Nehring, chairman of the San Diego County GOP Central Committee. He said he doesn’t believe a compromise with Democrats is likely.

Schwarzenegger has threatened to bypass the Legislature and take his plan to voters in a special election if he cannot get his way with lawmakers.

Democrats, meanwhile, are assembling their own war machine. This week, they established a political committee supported by a coalition of unions, education groups and advocates for the poor that will coordinate resources and strategy.

So far, the state’s largest teachers union, the California Teachers Association, has aired radio ads attacking Schwarzenegger’s budget proposal as bad for schools; the state’s largest nurses union has run TV ads criticizing his decision to loosen hospital staffing rules and a proposal to eliminate the Board of Registered Nursing; and a pro-consumer group has been flying an airplane towing anti-Schwarzenegger banners wherever he’s made recent public appearances.

The ever-popular governor has hit the road, taking his case directly to the voters. He’s also returned to the bully pulpit of talk radio, which he used effectively during the 2003 recall campaign and last year, to push his plans.

The GOP convention, said California Republican Party spokeswoman Karen Hanretty, is “the first step in mobilizing them for a potential special election.”

At the heart of Schwarzenegger’s reform agenda are four measures aimed at reducing the clout of public employees and teachers, and ending the power of incumbency in Sacramento.

He wants to convert the state’s public pension program to a 401(k)-style system, require merit pay for teachers, and redraw congressional and state legislative boundaries to make the seats more competitive. He also wants to establish a mechanism that would automatically cut state spending when it exceeded revenue.

Schwarzenegger called a special session of the Legislature last month to push his proposals; they’ve gone nowhere. Instead, both sides are preparing ballot initiatives to qualify for a fall special election.

To date, both sides have submitted nearly 70 measures on a wide variety of issues that could end up on the ballot if a special election is called.

While Democrats may persuade voters to pass some of their initiatives, it’s still a risky strategy because Schwarzenegger will succeed with some of his agenda too, said Garry South, a former adviser to Gov. Gray Davis and longtime Democratic strategist.

Still, Schwarzenegger has yet to be truly tested, according to South.

“He’s lived a charmed political life so far,” South said. “He’s been able to pick the low-hanging fruit. This will be different.”