CALIFORNIA ELECTIONS / U.S. SENATE : Senate Hopefuls Spend $9 Million in Six Weeks : Campaign: Some of the 10 major candidates are running low on funds to use on last-minute advertising.

Ten major candidates spent a total of more than $9 million during a recent six-week period in a late push to capture their parties’ nominations for the two U. S. Senate seats in the California primary election, according to fund-raising reports released Thursday.

With only a dozen days remaining until the June 2 primary, the candidates had an additional $5.1 million in their campaign war chests to spend on last-minute television ads.

The reports, covering the period between April 1 and May 13, provide a glimpse into how the final days of the campaign will shape up.

Rep. Barbara Boxer (D-Greenbrae), despite raising $4.6 million overall, had far less cash on hand than her opponents in the Democratic primary for the six-year seat being vacated by Sen. Alan Cranston. Boxer had only $335,001 left, compared with $1.4 million for Rep. Mel Levine (D-Santa Monica) and about $1 million for Lt. Gov. Leo McCarthy.

“We’ve always known that we would be outspent and, of course, more dollars at the end would be helpful,” said Rose Kapolczynski, manager of the Boxer campaign. “But . . . our fund raising continues to be strong. I think we are going to be very competitive on the airwaves.”

Kapolczynski said the Boxer campaign has already paid $1 million in TV advertising for three commercials currently being aired throughout the state.

The three Democrats so far have raised more than $13 million in the most expensive primary race. Levine is the overall leader with more than $6 million in total receipts.

On the Republican side, Rep. Tom Campbell (R-Stanford) enjoys a comfortable fund-raising advantage over his primary opponents. Campbell reported $479,979 on hand, compared with $196,938 for former television commentator Bruce Herschensohn and $16,567 for former Palm Springs Mayor Sonny Bono.

Campbell has proven a formidable fund-raiser, with about $4 million in receipts--an amount the Northern California lawmaker needs to promote his candidacy in voter-rich Southern California, said one Herschensohn strategist.

“He’s got to spend three to four times more money in the Los Angeles media market to beat us,” said Ken Khachigian, campaign manager for Herschensohn, who is well known in Los Angeles after years of working as a commentator on television and radio.

Campbell outspent Herschensohn nearly 3 to 1 in the reporting period, $2.3 million to $798,667.

The reports reveal that the Bono campaign failed to muster the necessary financial strength it needs to mount an effective challenge. Bono has raised only $296,605 overall. None of the other nine major Senate candidates collected less than $2 million.

In the two-year seat, Republican primary front-runner John Seymour had a commanding fund-raising lead over Rep. William E. Dannemeyer (R-Fullerton). Seymour, who was appointed to the Senate by Gov. Pete Wilson, had $317,956 to spend while Dannemeyer had $50,557.

In addition, Seymour outspent Dannemeyer by more than 2 to 1 in April and part of May.

In the Democratic primary, former San Francisco Mayor Dianne Feinstein raised $1.2 million more than state Controller Gray Davis, but had nearly $200,000 less on hand.