Along the south shore of San Francisco Bay, from the bookstores of Palo Alto to the estates of Atherton, one man's checkbook has created an Assembly race where it otherwise wouldn't exist.

In a district dominated by Democrats, Republican Steve Poizner has spent $4.8 million of his own money -- writing checks of $100,000 or more to himself every week since August -- to pay for a blizzard of television ads and mailers, and has raised $1 million more.

Other California millionaires have tapped their fortunes while trying to get elected governor or controller, but nobody has ever spent so much of his own money to win a seat in the raucous, 80-member Assembly -- what's considered an entry-level job in Sacramento.

Poizner has spent so much that the Democrats who tally campaign contributions in key legislative races have stopped counting it and type "irrelevant" in the Poizner column.

Campaign workers for his Democratic opponent, Ira Ruskin, amuse themselves by figuring out what else Poizner's expenditures could have bought, such as a six-bedroom Mediterranean-style house with pool in Palo Alto or a GOP-logo shirt and hat for every Republican registered in the district -- all 77,000.

They might be wowed by Poizner's largess, but Democrats take him seriously and have poured more than $782,000 into Ruskin's campaign -- half of the $1.3 million he has raised since January.

At the same time, they say they are confident that presidential politics, which has heightened partisanship in the district, will work in favor of the candidate with the "D" beside his name. Four years ago, only 35% of district voters chose George W. Bush. Last year, 61% of voters rejected the recall of Democratic Gov. Gray Davis.

Poizner is "a Republican attempting to capture a seat that is safely Democratic in a district that, by a wide margin, is likely to vote for John Kerry and Barbara Boxer," said Allan Hoffenblum, a Republican consultant and publisher of the Target Book, which analyzes legislative races. "If Poizner wasn't spending enough money to make himself a household name, then no one would be taking his campaign seriously."

Democrats recognize the appeal of Poizner, a socially liberal, business-minded Republican in a region known for its universities and entrepreneurs. The district leans left -- voter registration is 45% Democratic and 31% Republican -- but has elected moderate Republicans in the past, such as former Assemblywoman Becky Morgan and former Rep. Tom Campbell.

Campbell notes that he was first elected to Congress in 1988, when Republican George H.W. Bush was rejected by area voters.

Campbell said he was confident that Poizner would win because his brand of Republicanism -- which says government should be restricted to only what is necessary -- resonates with the many successful, self-made people in the district.

Poizner, of Los Gatos, won the endorsement of the San Francisco Chronicle and the San Jose Mercury News -- two newspapers that also endorsed Kerry.

"If you had to construct the ideal Republican to run in this district, it would be Steve Poizner," said Bill Whalen, a senior research fellow at Stanford University's Hoover Institution and a paid policy consultant to Poizner. "He's like Arnold Schwarzenegger."

On Monday, Republican Gov. Arnold Schwarzenegger led a rally at a Menlo Park hotel for Poizner, casting him as an independent-minded candidate in the Schwarzenegger mold.

Like himself, the governor said, Poizner is an entrepreneur who has the money to resist the "special interests" inundating the capital.

"People are sick and tired of the typical politicians that work their way up through the halls of Sacramento," Schwarzenegger said. "But when they get in there, they're owned by the special interests. He's an outsider."

Schwarzenegger added: "This man, Steve Poizner, cannot be bought by the special interests. Let me tell you something.... He can laugh at the special interests when they say we're going to give you $25,000 for your campaign, and in return you do this or that for me."

Democrats don't deny that Poizner has a compelling story.

The 47-year-old Texan and Stanford business school graduate made his wealth founding a company that uses satellite technology to pinpoint the location of cellphone and pager users. The company, SnapTrack, was sold to Qualcomm for $1 billion in 2000.