The House resignation last week of newly confirmed Securities and Exchange Commission Chairman Chris Cox kicked the race to succeed him in California’s 48th district into overdrive, as the two top GOP candidates each basked in high-profile endorsements.

Cox’s departure from Congress last Tuesday started the clock for Gov. Arnold Schwarzenegger (R) to schedule a special election. Under state law, Schwarzenegger has 14 days to set the date, making it likely that the primary will take place some time in October and the runoff election in December.

Before Cox, a Republican, even left the House, state Sen. John Campbell (R) and ex-state Assemblywoman Marilyn Brewer (R) were already running hard to take over his heavily GOP district.

“We started ramping up before the resignation,” said Dave Gilliard, a consultant for the Campbell campaign.

Campbell got some good news last week in the form of a rare official endorsement from Schwarzenegger. Though the governor’s popularity has dropped in recent months as he has grappled with legislative and political setbacks, the endorsement is still considered valuable.

Gilliard predicted the impact of the Schwarzenegger endorsement would be “huge.”

“It’s huge because it’s rare, and the voters out here know it’s rare,” he said.

But Brewer appears to have scored some high-profile backing of her own. Ken Khachigian, the Republican lawyer who serves as California point man for Sen. John McCain (R-Ariz.), said McCain would be endorsing Brewer soon.

“I was told it was a done deal,” Khachigian said of the endorsement, which was first reported by the Orange County Register.

McCain’s office did not return a call seeking comment, but Khachigian said that the Senator would back Brewer because “John is loyal to his friends.”

Brewer was one of only a handful of Republican officeholders in California to endorse McCain during the 2000 presidential primaries, campaigning all over the state for him at a time when much of the state’s GOP establishment was supporting George W. Bush.

On the financial front, Brewer consultant Harvey Englander said the candidate had now loaned her campaign a total of $300,000 and that they had received donations or firm pledges for another $150,000.

Gilliard said Campbell had already raised more than $400,000 and would be opening a campaign headquarters within the next few days.

Campbell’s campaign will be run by Jim Terry, whose past work includes stints with Rep. Ed Royce (R-Calif.) and the National Republican Congressional Committee. Arnold Steinberg will do polling, and Keelen Communications will handle Washington-based fundraising.

Campbell’s campaign will likely focus on his experience and solidly conservative credentials, while Brewer’s will emphasize her similarly conservative economic views while also touting her moderate positions on social issues — a profile that she believes is better-suited to the affluent district centered on Newport Beach.

Gilliard was dismissive of the charge that Campbell might somehow be too conservative for the 48th district. “The response is that Chris Cox and John Campbell agree on almost every issue,” he said, pointing out that Cox was re-elected with ease numerous times.

Indeed, highlighting Campbell’s similarities to the previous holder of the seat will be a key part of the state Senator’s strategy. Campbell’s Web site prominently features a picture of the candidate with Cox.

But Englander argued that Cox’s numerous re-election victories did not necessarily indicate that the district was just as conservative as he was, because most Congressional incumbents today are regularly re-elected anyway. He also disputed the idea that Campbell carried as much stature as Cox.

“He’s not even Chris Cox lite. He’s Chris Cox ultra-lite,” Englander said.

Beyond the basic moderate vs. conservative divide, the ideological battle within the primary could be further complicated if more candidates jump in. Ex-GOP Rep. Bob Dornan (Calif.) is reportedly considering a third-party bid, as is anti-immigration activist Jim Gilchrist, who is best known for founding the Minuteman Project along the Arizona-Mexico border.

Neither of those two men has said whether they will run yet, but if one or both of them does, they could cause trouble for Campbell by splitting the conservative vote.

Under California’s system, candidates from all parties will run together on the same October primary ballot. If no candidate receives at least 50 percent of the vote, then the top finisher from each party proceeds to a runoff election two months later.

No Democrat has expressed an interest in the race yet. President Bush won the district in 2004 with 58 percent of the vote.