Financial disclosure forms for this year's House and Senate races show few exceptions to the rule that incumbents have the edge in fund raising, according to a Federal Election Commission analysis released Saturday. Candidates raised $279 million and spent $192 million from January 1989 through the end of June, the analysis says. The candidates still in this year's races reported having $158.8 million available to spend for the November elections. The data confirm the overwhelming advantage of incumbents, particularly in receiving donations from special-interest political action committees. Proposals to significantly restrict or even prohibit PAC donations and other incentives designed to level the playing field for challengers are included in campaign-finance overhaul plans now before Congress. Overall, when races for open seats are excluded, four of every five dollars donated to congressional candidates went to incumbents. The 441 incumbents seeking re-election to House or Senate seats reported raising a total of $196 million in the 18-month period covered by the study, with $74 million of that total coming from PACs. Including primary races there were nearly twice as many challengers _ 793 _ but they raised just $46 million, with $6. 3 million coming from PACs. The total of challenger loans to their own campaigns eclipsed their overall PAC receipts by more than $1 million. But challengers have matched or even surpassed incumbents in raising money in a dozen races, some of them this year's hottest contests. In Oregon, for example, Democratic challenger Mike Kopetski is essentially even with incumbent Republican Rep. Denny Smith in a race considered a toss-up. And in California, actor Ralph Waite, running as a Democrat, reported raising $235,000 as of June 30, more than twice the total raised by incumbent Republican Rep. Alfred McCandless. Two Virginia races have challengers beating their opponents at fund-raising. Democrat James Moran, mayor of the Washington suburb of Alexandria, reported a slight edge over incumbent Republican Stan Parris. Republican Rep. Frank Wolf is expected to keep his seat but is being beaten at the fund-raising game by Lyndon LaRouche, the perennial fringe presidential candidate who is running despite being in a federal prison for a fraud conviction. In Senate races, where six-year terms give plenty of time to raise money, incumbents enjoy huge fund-raising edges. The king of Senate fund-raising is Republican Phil Gramm of Texas, who raised $8.9 million from January 1989 through June alone, and as of June 30 reported $6.2 million in the bank. Democratic challenger Hugh Parmer had raised $1.4 million over the 18 months but had just $20,500 left to enter the final months of the campaign. Not far behind Gramm was New Jersey Democratic Sen. Bill Bradley, who is considered a possible presidential candidate in 1992. Bradley raised $6.7 million over the 18-month period and had $4.3 million in the bank at the end of June. Republican challenger Christine Todd Whitman raised $228,000 and had less than $75,000 on hand. On the House side, members of the Democratic leadership have the biggest advantage. For example, Missouri Rep. Richard Gephardt, the House majority leader and another potential 1992 presidential candidate, raised nearly $1 million over the 18-month period. His Republican challenger, Malcolm Holekamp, collected just $18,436.