Former Rep. Tom Campbell may be leading in Republican primary polls for California Senate, but observers on the West Coast and in Washington, D.C., say the bigger issue is whether he’s leading in the fundraising race come April 15.

That’s the deadline for federal candidates to file fundraising reports for the first quarter of 2010, and it represents an important test for the Campbell campaign as it seeks to prove the former college professor and Congressman can muster the resources to wage a competitive race against Sen. Barbara Boxer (D).

Campbell does not have a reputation as a fundraising juggernaut; in a 2000 challenge to Sen. Dianne Feinstein (D), he raised $4.7 million to the incumbent’s $10.5 million.

“The financial side is the 800-pound gorilla” in the GOP race, said one chief of staff for a Republican House Member from California who has not picked sides in the primary race. “When you’re taking on an incumbent like Barbara Boxer … it’s going to take financial resources to communicate a message.”

Given that, most observers still give former Hewlett-Packard CEO Carly Fiorina the edge on the Republican side, even though Campbell leads her and state Assemblyman Chuck DeVore in recent primary polls. Campbell was the only one of the three to lead Boxer in a March Field poll.

“Carly’s got an advantage. She doesn’t have a problem raising money, and she’s also able to write herself a check,” said Johnny Amaral, the chief of staff for Rep. Devin Nunes (R-Calif.), who is supporting Fiorina. “Just having the ability to do that in a state like California is huge.”

Fiorina’s already put $2.5 million of her own money into the race, though campaign manager Marty Wilson told Roll Call that he has not “talked to her about putting any more money in and don’t know that I will.” And Wilson confirmed her first-quarter fundraising report will not show another substantial personal contribution.

The House chief of staff whose boss is unaligned in the race said it’s too early to draw much from general election polls until after the June 8 primary. “After June, that’s when the numbers are really going to start to take shape. Everything else is just posturing right now.”

However, Tim Clark, a longtime California Republican consultant, said the polls will mean a lot if Campbell has money. He said if Campbell “shows a couple million bucks, then all of a sudden it’s a game-changer.”

And the Campbell campaign has been upbeat about its fundraising, touting its totals in February and again in March, when it crossed the $1 million threshold. Bay Area fundraising consultant Kristin Hueter said the campaign is now up to $1.2 million, despite the fact that it did not start fundraising in earnest until the last week of January. By comparison, Fiorina raised $1.1 million in the fourth quarter of 2009.

However, the Fiorina campaign highlighted the fact that Campbell’s fundraising pace has slackened — after announcing $700,000 raised in February, Campbell raised just $300,000 from February to March to get to $1 million.

Hueter denied there is any prolonged slowdown and said the campaign is poised to see a big jump in receipts in the coming weeks. “March is when we’ve started our events,” said Hueter, a veteran fundraiser who also oversees Bay Area fundraising for California gubernatorial candidate Meg Whitman (R) and worked for former Massachusetts Gov. Mitt Romney’s 2008 presidential campaign.

The Campbell campaign is drawing a big chunk of its money from Silicon Valley, which is not surprising since he represented two different House districts in the area for five terms. Hueter estimated that close to three-quarters of Campbell’s cash so far has come from the Bay Area, which encompasses the Valley, as well as San Francisco, Oakland and their surrounding suburbs.

What is more surprising is that Southern California — and not the Bay Area — is the main source of Fiorina money, even though she lives in Silicon Valley and was the high-profile CEO of one of the region’s pre-eminent companies. Just a handful of Fiorina’s finance “leadership team” hail from the Bay Area — the vast majority are in Southern California.

“Historically that’s where Republicans raise the majority of their money, and of course, that’s also where the votes are,” Wilson said. “You’ve got to go hunting where the ducks are.”

But the Campbell campaign says it is telling that many of the Silicon Valley’s tech and venture capital leaders have gotten behind Campbell. “These are … very important business people in the area who know both Tom Campbell and Carly Fiorina and made a choice to be with Tom,” said Richard Temple, one of Campbell’s general consultants.

It’s no secret that Fiorina made her share of enemies in Silicon Valley thanks to her controversial tenure at HP, where she publicly feuded with the Hewlett and Packard families over the direction of the company. The anti-Carly sentiment in segments of the Silicon Valley community remains strong, and it is something “I think she has to contend with,” Clark said.

Wilson predicted Fiorina “will have more than her fair share of Silicon Valley money.” Regardless, her fundraising operation is clearly broader than Campbell’s. In addition to Southern California, the campaign has also actively been raising money in the inland San Joaquin Valley, as well as out of state.

Fiorina has already done multiple fundraising events in Florida, New York and Washington, and she is conducting one in Seattle today. The campaign plans to head back to D.C. for more fundraising before the primary election, and Wilson estimated that 20 percent of the campaign’s cash would ultimately come from out of state.

Campbell, in contrast, has pushed off events in New York and D.C., and he does not plan on leaving California before the primary.

The question for Campbell is whether he can compete with Fiorina’s more expansive financial reach in the primary, not to mention Boxer’s in the general.

Clark echoed Wilson in noting that “most of the Republican money still comes out of L.A. and Orange County, and I think Fiorina’s pretty well-established there.” He also said that Wilson is “fantastically connected with the finance community, so that’s a real advantage for her.” Fiorina has also retained Cassandra Vandenberg, Sen. John McCain’s (R-Ariz.) California fundraising consultant for his 2008 campaign, as her finance director, which has helped her rein in a number of McCain’s California bundlers.

But Hueter noted that Republican campaigns can rely on the Bay Area to raise significant cash — Romney raised about the same out of the Bay Area and Northern California as he did out of Southern California for his presidential campaign. And she said Whitman has raised more for her gubernatorial race from Bay Area as well.

As for the general, Clark predicted that Orange County and Los Angeles money would start flowing to Campbell should he become the nominee. But Wilson differed. “Fundraising just doesn’t happen because you’re the nominee. If either Campbell or DeVore is the nominee, he said, “donors will realize it’s more of the same running against Barbara Boxer, and my guess is they will largely sit on their wallets.”