Getty Images

Republican Senate candidate Carly Fiorina

Carly Fiorina, the former chief executive of Hewlett-Packard, won the Republican nomination for the U.S. Senate on Tuesday, setting the stage for what is certain to be a focused effort by her party to topple Barbara Boxer, the Democratic incumbent, who has held her Senate seat for nearly two decades.

Fiorina beat out Tom Campbell, a former congressman from San Jose, and Chuck DeVore, a conservative assemblyman from Orange County, who enjoyed some support from the Tea Party movement.

On the Democratic side, Boxer ran virtually unopposed. November’s general election is now expected to be one of the most closely watched – and bitterly fought – battles in the country, a barometer of what could be a Republican resurgence.

With Fiorina’s victory widely expected and Boxer’s nomination assured, the fisticuffs had already begun by late last week, when Fiorina aired TV attack ads against Boxer.

The liberal senator’s perceived vulnerability is not new – Republican strategists have targeted Boxer in past elections – but there is a sense in both parties that she could fall victim to anti-Washington, anti-incumbent discontent that Democrats fear is surfacing across the country amid a persistent recession.

“The president has been spending a lot of time out here fundraising, which has raised questions about her vulnerability,” said Mark Baldbassare, the president of the Public Policy Institute of California, a nonpartisan group in San Francisco that frequently publishes studies of voter sentiment.

“The biggest issues now are the economy, budget and education,” Baldassare said. “And it’s a very difficult environment for incumbents.”

Meanwhile, Fiorina's win in Tuesday’s primary punctuates the brisk rise of a political neophyte.

After rising from a secretarial position to become one of the biggest names in American business management, Fiorina, 55, pitched herself as a self-made, politically green but financially savvy “CEO of California” at a time when economic and budget worries were foremost on voters’ minds.

In her acceptance speech to supporters, Fiorina aligned herself with another high-profile businesswoman who won a Republican nomination on Tuesday: Meg Whitman, the former eBay executive who is running for governor against California Attorney General Jerry Brown.

"California will now be offered two candidates at the top of our ticket who’ve actually created jobs and cut costs, and we are looking forward to taking on the two career politicians on the other side," Fiorina said.

During the primary race Fiorina was pressed to take a conservative tack to compete with DeVore and appeal to the state’s base of roughly 20 million Republicans. Fiorina opposes abortion and gay marriage.

In her television spot attacking Boxer last week, Fiorina compared Boxer’s characterization of climate change as a national security threat to “worrying about the weather.”

Fiorina recently won an endorsement from two Republican Party heavyweights: Senate Minority Leader Mitch McConnell and Sarah Palin. That, combined with solid fundraising and her willingness to personally bankroll the campaign – she has contributed about $5 million – made Fiorina a formidable candidate, experts say.

“It’s a combination of money, name recognition, somebody who improved as a candidate,” said Ethan Rarick of the Institute of Governmental Studies at UC Berkeley. “A lot of the Republicans see Campbell as much too moderate. They don’t like Campbell and never have. DeVore had very little money. When those are the opponents and you’ve got a well-funded candidate who has fairly broad appeal within the Republican party, I think it’s not surprising that she won.”

If there was talk early on that elements like the Tea Party could lift a staunch conservative like DeVore to the nomination, it dissipated when he ran into fundraising problems, especially in a state as big as California.

And now that the primary is over, Fiorina is expected to shift to the center, observers say, in an effort to claim the 20 percent of California voters who identify as independent.

A recent poll conducted by the Los Angeles Times showed that Campbell, the more moderate candidate, would beat Boxer by 7 points in a head-to-head matchup, while Fiorina is trailing the Democrat by six.

“It’s absolutely a race to the center,” said Baldassare. “They’re both going to portray each other as out of touch.”

In a telephone interview, Boxer’s campaign manager, Rose Kapolczynski, said Fiorina’s positions on the environment and gun control do not reflect views that most Californians hold, and challenged Fiorina's claim that she can bring jobs back to California, which has one of the highest unemployment rates in the nation.

“Fiorina has a clear record in the past on jobs—she shipped 30,000 jobs overseas when she was at HP,” Kapolczynski said. “She describes herself as a proud pro-life conservative that’s out of sync with a majority of Californians.”

Observers say the statewide battle will turn out to be extremely expensive, which could be advantageous to Fiorina. It will be one of the most high-profile races in the country and, as evidenced by President Obama’s early visits out west, both sides could continue to draw a bevy of big names into their respective efforts.

“You go from a primary where a third of the voters are expected to turn out and the focus is on those 5 million voters who are Republicans,” said Baldassare, to an election in which turnout could surpass 50 percent and the focus will turn to reaching out to a diverse majority.

“It’ll get very interesting,” Baldassare said.