Vice President Bush, accused by his prospective opponents of skirting the edges of federal campaign finance law, has amassed $3.9 million, 24 staffers and nine consultants to build the largest organization of any of the potential 1988 presidential candidates.

Housed in 11,000 square feet of space in downtown Washington, the Fund for America's Future, Bush's political action committee (PAC), is expected to emerge among the nation's top three or four independent PACs, even though it was not established until last May.

The Bush PAC has become the center of an increasingly bitter controversy among prospective Republican presidential candidates, many of whom accuse Bush of using his PAC as an illegal vehicle to finance the early stages of a presidential bid.

The skirmishes, many of which are being played out before the Federal Election Commission, may seem arcane, but they could play a significant role in the fight for the 1988 Republican nomination.

The 1988 GOP contest appears destined to become the longest and most expensive in history, and the ability to finance a sustained campaign may prove critical to the outcome. In this context, what "multicandidate" PACs, such as Bush's, can and can't do with their funds becomes especially important.

The PACs offer prospective candidates major advantages. Unlike a presidential campaign fund, which can accept a maximum of $1,000 from an individual, a multicandidate PAC can accept $5,000 every year. In addition, expenditures of multicandidate PACs do not count against presidential primary campaign spending limits, which can severely restrict campaign activities in states such as New Hampshire.

These PACs can be used to build support by giving $5,000 contributions to House and Senate candidates, and to finance travel for speeches on behalf of those congressional candidates.

And, whatever the law is, these special multicandidate PACs have been used to perform the preliminary presidential spade work, developing direct-mail donor bases, paying for all kinds of travel and keeping a small cadre of aides on the payroll.

The Fund for America's Future represents a major advance in the weaponry of presidential campaigning. In the past, such candidates as Walter F. Mondale and Ronald Reagan have set up special PACs to fill the financial void in the phase before candidacy is declared.

"This is the first time that an individual Bush who has a multicandidate PAC has this type of operation, or at least one this visible," William Phillips, executive director of the Fund for America's Future and former executive director of the Republican National Committee, said.

"When they [Congress] set up the laws and regulations, they really didn't take this type of operation into account. . . . But its's obviously beginning to have some impact. So I don't know what will happen," he said.

The legality of the activities of the Bush PAC has been indirectly challenged by former Senate majority leader Howard H. Baker Jr. (R-Tenn.), who asked the FEC to determine what his own multicandidate PAC may and may not do. The FEC opinion suggested that some Bush PAC expenditures are legally questionable.

The Bush PAC has countered with it own request for an FEC opinion, and many strategists working for Bush's potential opponents hope the FEC will restrict the activities of the vice president's operation.

The Fund for America's Future has the earmarks of a presidential campaign in miniature:

*As chairman, it has hired Lee Atwater, deputy campaign manager of the Reagan-Bush '84 Committee, who will work about half time for the Bush PAC for an annual fee in the range of $100,000, according to Phillips. The fund also hired Helen Cameron, who ran voter registration for Reagan-Bush, as political director.

*There is a network of four regional political directors: Jim Shearer, who has responsiblity for the Southwest and grain belt states; Andy Carter, the West; William Hussey, the Northeast and the Midwest, and Graham Tew, the South.The fund has hired full-time staff in Iowa and Michigan, and plans to hire local workers for New Hampshire. These are key early states in the 1988 presidential contest. In Michigan, where a 1986 precinct delegate contest effectively starts the 1988 race, the Bush PAC has hired three full-time staff members.

*The fund has a staff of three researchers and has consultant contracts with Fred Bush, a major donor fund-raising specialist; Odell, Roper and Associates, direct mail; Craig Shirley, who works with youth and conservative groups; Roy Hale, an accounting specialist, and Jan Baran, an FEC lawyer.

*Of the $3.9 million raised in 1985, Phillips said about $150,000, less than 4 percent, has been given to candidates, supposedly the central purpose of the organization.

This relatively low ratio of candidate contributions to total cash raised is not unique among prospective presidential candidates. The Campaign for Prosperity, the multicandidate PAC run by Rep. Jack Kemp (R-N.Y.), last year raised $1.2 million, of which $32,403 was given to candidates.

The Kemp PAC maintains a largely clerical staff of five and retains five consultants, the highest paid of whom is the director, John Maxwell, who gets $70,000.

Baker maintains the Republican Majority Fund, which last year raised $741,229 and gave a total of $263,323, according to James Cannon.

Cannon is the Baker Fund's highest paid consultant; he gets $5,000 a month for eight days' work, and an extra $1,000 for every day above eight. Last year, he receive $82,500 from the Republican Majority Fund.

The highest paid of all the PAC chairmen and managers, however, is Donald J. Devine, former director of the Office of Personnel Management, who gets $150 an hour for up to 20 hours of work a week -- the equivalent of $150,000 a year -- from Campaign America, the PAC run by Senate Majority Leader Robert J. Dole (R-Kan.). For Dole, who has been criticized by some conservatives, Devine, a hero of the new right, adds a patina of right-wing legitimacy.