Del Beccaro, 53, is a Contra Costa County lawyer who specializes in the breakups of business partnerships.
He led the state party from 2011 to 2013, a period when Republicans lost elections for every statewide office and suffered a historic blow as Democrats won a two-thirds supermajority in both houses of the Legislature for the first time in more than a century.
In a written statement on his candidacy, Del Beccaro called for simplification of the federal tax code and vowed to ensure "that prosperity is not limited to the well-connected."
"Californians deserve to have a tax system that favors everyone, not just the rich," he said.
Del Beccaro's conservative profile will make his campaign an uphill climb in a state that strongly favors Democrats.
In a telephone interview, he said the science on global warming was unsettled, and therefore federal policy should not presume that human activity is causing climate change.
Del Beccaro has described himself as “pro-life” on abortion. He supported
In the interview, Del Beccaro called for the repeal of Obamacare, but only if Republicans replace it with a better healthcare law. One provision that should be kept, he said, is the one allowing young adults to remain on their parents' health plans until they are 26.
The other main Republican in the Senate race is state Assemblyman Rocky Chavez of Oceanside. Chavez's lackluster fundraising in his campaign's first few weeks -- he reported less than $5,000 in the bank at the end of March -- has raised questions about his viability.
The major Democrat in the race, state Atty. Gen. Kamala Harris, reported more than $2.2 million in cash on hand at the end of March.
Allan Hoffenblum, a former Republican consultant who publishes the nonpartisan California Target Book election guide, described Del Beccaro as a "showman" whose candidacy would be hard to take seriously.
"I think it's an ego thing for him," Hoffenblum said, comparing Del Beccaro to presidential candidates who aim less for the White House than for lucrative TV and radio jobs that can follow a high-profile campaign.
Del Beccaro said he expected to tap the statewide networks he cultivated as party chairman to raise as much as $10 million for the campaign. He also said he did not deserve blame for the the party's poor election results on his watch.
"There were far greater factors than I involved in that process," he said, citing the heavy turnout of Democrats for the 2012 presidential election and labor's costly campaign against a California ballot measure that would have curbed union spending on politics.
Del Beccaro was raised in Huntington, N.Y., a Long Island suburb of New York City, and the East Bay. He said his experience mediating business disputes was part of what qualified him for the Senate job.
"Business partners fighting -- it's worse than divorce court," Del Beccaro said. "It's very contentious."
In his announcement, he called for a federal "flat tax." He said he was still working on details but expected his plan to include just one or two income tax rates.
He also vowed a dramatic cut in deductions -- but not those for mortgage interest or charitable donations -- with the goal of eliminating giveaways to corporations and the wealthy.
"This may sound kind of populist," he said, "but I'm against using the tax code to exploit relationships and get better deals."