If one race in the country epitomizes how the conservative wing of the Republican Party has evolved through the years, it might be the contest in California’s 3rd district, where three strong Republicans are vying in the March 2 primary to replace retiring Rep. Doug Ose (R).

One of the major contenders for the Sacramento-area seat is former state Attorney General Dan Lungren, who represented the Long Beach area in Congress from 1978 to 1988. In the 1980s, Lungren was a staunch law-and-order Republican, a close ally of Ronald Reagan’s, and was frequently described as one of the most conservative Members of the House. He routinely racked up low-single-digit scores from the liberal Americans for Democratic Action, and scored in the high 90s from the American Conservative Union.

But Lungren is not regarded as the conservative in the field. That distinction belongs to state Sen. Rico Oller, who has branded Lungren a moderate and pounded him for his less-than-absolutist positions on issues such as immigration and gun control.

There is also a genuine moderate in the field — real estate developer Mary Ose, the Congressman’s older sister. But while she has been endorsed by the centrist Republican Main Street Partnership, Ose too is touting her conservative credentials — at least on fiscal matters.

“She can go toe-to-toe with anyone when it comes to talking about fiscal restraint and bringing back tax dollars to California,” said Beth Pendexter, Ose’s spokeswoman.

While the district’s lines have changed due to redistricting to take in more rural areas, its evolution is nevertheless striking. Rep. Vic Fazio (D) represented the 3rd for two decades, followed by Doug Ose, a leading House moderate. Now, Oller, the most conservative candidate in the primary field, is the nominal favorite.

“It’s probably Oller’s race to lose,” said Dan Schnur, a Sacramento-based Republican consultant who is not working for any of the candidates in the race.

The primary is paramount, which is why the final days have been so intense. The winner will face Gabe Castillo, a financial adviser who is billing himself as a conservative Democrat, in November, though the Republican will be heavily favored.

“We’ve always said the [primary] race is for second place,” boasted Steve Davey, Oller’s campaign manager.

Certainly the most recently released public poll — Oller’s — bears that out. In the survey of 300 likely GOP primary voters conducted Feb. 10 and 11, Oller was preferred by 32 percent of the respondents, Ose by 22 percent and Lungren by 19 percent. The rest of the voters were divided among minor candidates or undecided in the poll, which had a 5.7 percent margin of error.

But a Lungren poll in January showed him slightly ahead. And in an expensive, increasingly nasty race with plenty of TV and radio advertising, anything can still happen.

Oller and Ose will both spend in excess of $1 million on the primary; Lungren has about half that much.

“It’s an interesting family feud,” said Allan Hoffenblum, a GOP consultant and publisher of the California Target Book, a primer on Golden State elections. “You really have three distinct campaigns, and you’re seeing three distinct strategies.”

Ose, in particular, appears to be the wild card. Although her family is well known in Sacramento-area business circles, Ose is a political novice — just as her brother was when he was elected to Congress in 1998 — who jumped into the race at the last possible moment in December 2003.

She has poured almost $800,000 of her own money into the campaign to date — triggering the “millionaire’s amendment” that enables her opponents to raise more than the legal limit from individuals — and has aired several commercials in which she introduces herself as a plain-spoken citizen rather than a career politician. The ads appear to be working, and Ose’s standing in the polls, by all accounts, is rising.

“We’ve been feeling the momentum for the last couple of weeks,” Pendexter said.

This week, the Republican Main Street Partnership began airing ads on Ose’s behalf. The tough spots revisit charges of spousal abuse that were leveled against Oller several years ago and remind voters that Oller favored conservative state Sen. Tom McClintock (R) rather than now-Gov. Arnold Schwarzenegger (R) in the 2003 California recall election. Oller has replied with an ad accusing one of Ose’s businesses of failing to pay taxes and reminding voters that she was once a Democrat.

Ose is up with an ad of her own showing actors who look like her two male opponents slinging mud at each other. One school of thought says the two conservative men will split their base of support, enabling Ose to sneak through the primary.

Even the Humane Society has gotten into the act. The animal rights group’s political action committee, Humane USA, has sent a flier to Republican voters and is running radio ads detailing Oller’s opposition to animal protection legislation in the Legislature, including his vote against a bill to toughen penalties for people who organize cock fights.

Davey, whose boss has been endorsed by the rival Club for Growth, blasted the Republican Main Street Partnership and suggested that the group is violating campaign finance laws that require an arm’s length between the candidates and the groups airing ads on their behalf. Doug Ose, he noted, is a member of the centrist group’s board of directors and heads its California chapter.

But the Oses and the Main Street Partnership deny any connection.

Meanwhile, Oller’s support among bedrock conservatives appears to be unshakable. In addition to the Club for Growth, several social conservative and anti-immigration groups are helping him.

If Oller has stumbled at all, it has been in his advertising. Oller was accused of being culturally insensitive when he sent out an anti-immigration mail piece with a picture of a man in a turban. He was also embarrassed earlier this month when Schwarzenegger — who is pointedly neutral in the primary race — asked Oller to stop running TV ads with the governor’s picture in them.

“If there’s anything, Oller has gotten some bad publicity,” Hoffenblum said. “You don’t want people talking about your TV spots or your mailers.”

But it is Lungren, the GOP nominee for governor in 1998, who may be in the strangest position.

Lungren, who has been out of politics and practicing law since 1998, said he decided to get back in after the Sept. 11, 2001, terrorist attacks, feeling the pull of public service.

“We’re selling Dan’s experience and what he’s going to do to help President Bush, just like he supported President Reagan,” said Brian Seitchik, Lungren’s campaign manager.

Lungren has snared far more high-profile endorsements from politicians and law enforcement officials than his primary foes, and also got the blessing of The Sacramento Bee, the biggest newspaper in the district. Seitchik noted that unlike his opponents, Lungren has already won in the district six times — every primary and general election during his three campaigns for statewide office.

Lungren is working hard to remind voters of his conservative credentials — appearing at a news conference Tuesday, for example, at which he condemned the “illegal acts” of San Francisco officials who are sanctioning gay marriages. But his record of occasional compromise while he served as attorney general and in the House — in the minority, forced to work with Democrats who controlled the chamber — has been fodder for the more contemporary, take-no-prisoners conservatism practiced by Oller and his allies.

“Lungren’s conservative credentials, while legitimate, seem dated,” observed Schnur, the GOP consultant.

As the centrist in the race by default, Lungren could pull a substantial amount of votes from Ose and Oller. On the other hand, he could be squeezed by two opponents whose supporters may be more dedicated.