When former California state Sen. Jim Costa (D) was first elected to the Legislature in 1978, Lisa Quigley, his opponent in March 2’s 20th district Democratic primary, was in junior high school.

That, as much as anything, explains Costa’s inherent advantage in the race to replace Quigley’s longtime former boss, Rep. Cal Dooley (D), who is retiring from the Central Valley seat after seven terms.

Costa, who spent 24 years in Sacramento before being term limited in 2002, has a long record of accomplishment — and even has a highway named after him. He has most of the institutional support among California Democrats, including Sen. Dianne Feinstein, and many voters think he’s still in office.

“With a month to go, it’s really hard to see how he would be defeated,” said former Rep. Richard Lehman (D), a one-time Central Valley Congressman who is supporting Costa.

But Quigley, 38, Dooley’s former chief of staff, remains undaunted. She is banking on recent demographic and political changes in the district to put her over the top.

She believes her newcomer tag will be more appealing to voters than Costa’s old comfortable shoe. And she is hoping that Californians’ antipathy toward Sacramento politicians outstrips their antipathy toward Washington, D.C.

“It’s quite clear that I’m the outsider, the fresh face, the one candidate with a plan,” Quigley said.

The 20th district race will perhaps be the most hard-fought — and expensive — Democratic contest on the California primary ballot. And with both Costa and Quigley going up last week with TV ads, it is only going to get nastier.

The primary winner will likely face state Sen. Roy Ashburn (R), a former top aide to House Ways and Means Chairman Bill Thomas (R), who represents an adjacent Central Valley district. But the Democrat will be favored, which is why the primary competition has become so intense.

Quigley, who has thrown more jabs than Costa to date, has accused her opponent of voting with polluters and the tobacco industry — and readily accepting their campaign contributions. She says he is resting on his laurels and ducking debates and has reminded voters that he was arrested for soliciting a prostitute in 1989.

Costa, a lifelong Central Valley resident, calls Quigley — who grew up in the valley and has always voted there but worked for a decade and a half on Capitol Hill — a carpetbagger. He delighted in the most recent campaign finance reports, which showed that most of Quigley’s contributions came from individuals and interest groups based in the D.C. area.

“We have been saying all along that I am the candidate from the [Congressional] district and Lisa Quigley is the candidate from Washington, D.C.,” Costa said.

The 20th district, which covers the wide swath of territory between Fresno and Bakersfield, has one of the highest concentrations of farmland in the nation. It is a Democratic — though fairly conservative — area with a majority-Hispanic population.

In the past, agribusiness has dominated the politics of the valley, and most successful politicians have tailored their records to the industry’s needs. Costa, whose family has farmed in the valley for generations, picked up the endorsement of one of the region’s powerhouses, the California Farm Bureau Federation, which has at times had a strained relationship with Dooley.

“Jim is a proven supporter of agriculture,” said Federation President Bill Pauli. “He values the role the state’s farmers and ranchers play in providing safe, affordable food, more than a million jobs and important environmental benefits.”

But Quigley has countered with an endorsement from Dolores Huerta, founder with the legendary Cesar Chavez of the United Farm Workers union (the union was born in Delano, which is in the 20th).

She was also endorsed at the same time by three Latina Members of California’s Congressional delegation, who criticized Costa’s record on air pollution, farm labor laws and immunizations for children of undocumented workers.

It is that new way of trying to appeal to the farming community that has defined Quigley’s campaign to date. While Costa may be tight with farmers, ranchers and other business leaders, Quigley is trying to show her solidarity with farm workers by talking about environmental laws and the health care of their families. She further tries to establish a connection by pointing out that she, too, is the mother of small children.

In a district where environmentalists are not always popular, Quigley is trumpeting her endorsement from the League of Conservation Voters (even though her patron, Dooley, received only a 25 percent score from the group in 2002).

Quigley is also touting her support from EMILY’s List — a sign, she says, of her commitment to the issue of reproductive health.

Despite the endorsement by Huerta — and Quigley would not say how she plans to deploy the popular Hispanic leader in the next few weeks — she is also pressing for an endorsement from the full UFW, so far without success. The union operates two popular Spanish-language radio stations in the Central Valley, and an endorsement could bring many people who do not regularly vote to the polls.

But Costa is also courting the farm workers. Give Kashkooli, the political director for the UFW, said the union is remaining on the sidelines for now — but noted that the attention from the candidates and their pro-labor rhetoric is a sign that power in the district is shifting.

“They’re running very differently than they would have 10 or 20 years ago,” Kashkooli said. “They’re more respective of farm workers and their needs in the community.”

Kashkooli said it would probably take some “dramatic, heartfelt action” by one of the candidates to merit an endorsement.

Reaching out to newer voters while attacking an opponent who is far better known, as Quigley is doing, may not translate into victory, however. Throughout his career, Costa was always attentive to the needs of his district — working particularly to improve the water supply and infrastructure that is so important to agribusiness and its work force. He was also adept at bringing home the pork.

What’s more, said Michael Fraioli, a D.C.-based Democratic consultant who is working for Costa, the 51-year-old candidate is a proven winner.

“You’re talking about a guy who’s had eight successful elections, including ’94, when he was the only Democrat [running for the state Senate in California] to defeat a Republican incumbent,” Fraioli said. “He knows how to do it. He knows you’ve got to put one foot in front of the other.”

Financially, the candidates appear to be on roughly equal footing. Costa did not begin raising money until last October, and took in $333,000 in the last three months of 2003. He finished the year with $263,000 in the bank.

Quigley, who had a month-long head start on fundraising, raised $201,000 in the last quarter of the year, $329,000 in all of 2003, and had $201,000 in the bank on Dec. 31.

Costa appears to be getting a late surge of financial support from the National Association of Realtors. The Fresno Bee reported Wednesday that the association is pouring more than $270,000 into the district on his behalf for radio ads that have already begun and TV ads that are scheduled to debut next week.

Quigley, as the underdog, is hoping that her TV and radio spots quickly close the evident gap in name identification.

“The opportunity to share my message with the voters is really key,” she said.