Reps. Barbara A. Mikulski and Michael D. Barnes, two liberal Democrats battling to become Maryland's next U.S. senator, have continued a fierce competition in fund raising and have received more than $800,000 each, according to campaign finance reports filed with the Federal Election Commission yesterday.

Gov. Harry Hughes, the third major Democrat running for the Senate, raised $417,329, according to the finance reports, which document campaign spending for the quarter ending June 30.

Mikulski has collected $868,583 compared with the $841,469 raised by Barnes. But Mikulski, who has a solid lead in the polls, has twice as much available to spend during the eight weeks remaining before Maryland's Sept. 9 primary.

The Republican Senate contenders continue to trail their Democratic counterparts: Baltimore businessman Richard Sullivan has raised $309,014, of which he contributed $200,000. Former White House aide Linda Chavez has raised $269,920 and Silver Spring attorney George Haley has raised $31,082.

Baltimore hotel owner Michael Schaefer, a little-known late entry into the race, said in an interview that he will file papers showing $694,183 in campaign contributions -- all but $22,991 in the form of a mortgage that he said he "may liquidate" for his campaign.

Among seven Democrats and three Republicans vying to succeed Barnes in the Montgomery County-based 8th Congressional District, a Republican, Del. Constance A. Morella, was the most successful fund raiser in the last quarter. Morella raised $125,587, followed by Democratic state Sen. Stewart Bainum Jr., who raised $114,933 between March 31 and June 30.

But Bainum, a wealthy Silver Spring businessman, continues to lead the field in total fund raising. He has $336,979, compared with Morella's $209,217.

Montgomery County Council member Esther P. Gelman, a Democrat, follows closely behind Morella, with $202,127 in funds raised to date. Leon G. Billings, a former U.S. Senate aide, has raised $127,830 and has spent all but $4,540 of it on an early media campaign.

In the hard-fought campaign to replace retiring GOP Rep. Marjorie Holt in the 4th Congressional District in Anne Arundel County, Democrat Tom McMillen maintained the fund-raising lead over Republican Del. Robert R. Neall. Although Neall for the first time raised more than McMillen in the most recent quarter -- $120,960 to McMillen's $85,980 -- McMillen has raised $354,260 overall, compared with Neall's $264,768.

John Pantelides, who is competing against McMillen for the Democratic nomination, said he has raised a total of $52,951, including $28,873 in the recent quarter.

In the Baltimore County-based 2nd Congressional District, first-term GOP incumbent Rep. Helen Bentley has raised $453,824 for her campaign, more than half of it collected last year. Democratic challenger Kathleen Kennedy Townsend, who entered the race earlier this year, has raised $303,393 to date, almost two-thirds in the most recent quarter.

Townsend currently has $182,036 cash on hand, compared with $116,115 in cash available to the Bentley campaign.

In the race to succeed retiring GOP Sen. Charles McC. Mathias Jr., the recent quarterly reports show that Mikulski, a former Baltimore social worker whose lead in the Senate campaign has already forced one opponent out of the race, is in a strong position to maintain her lead. She has $420,355 in cash on hand, compared with Barnes' $183,862.

Mikulski and Barnes, each of whom set goals of $1 million for the primary campaign, have raised more individually than any previous Senate candidates at this point in the election year.

Hughes, despite his status as a two-term governor, badly trails both. After an expensive, month-long media campaign designed to improve his standing in the polls, he has only $29,733 left in the bank.

Still, Hughes' campaign finance director, Andrew Robinson, said, "We're very confident based on the fund raisers we have planned between now and Sept. 9 that we'll be able to run a full and resourceful campaign."Staff writers R.H. Melton, Tom Vesey, Susan Schmidt and Gwen Ifill contributed to this report. CAPTION: Picture 1, Rep. Michael D. Barnes . . . has set goal of $1 million; Picture 2, Rep. Barbara A. Mikulski . . . has twice as much to spend.