Vice President Bush is overwhelming the opposition in early fund-raising for the 1988 Republican presidential nomination, pulling in cash at three times the rate of his nearest competitor.

Bush has amassed $5.4 million in just 11 months, allowing him to set up an operation with 32 full-time and nine temporary employes in Washington, Michigan, Iowa, New Hampshire and Texas. At the end of last month, the Bush political action committee, the Fund for America's Future, was sitting on a cash balance of $2.53 million.

In contrast, the PAC set up by Rep. Jack Kemp (R-N.Y.), Campaign for Prosperity, ended March in the red, with a cash balance of $139,209 and debts of $180,979. Campaign America, the PAC set up by Senate Majority Leader Robert J. Dole (R-Kan.), had a net balance of $411,949 at the end of February, and the Republican Majority Fund, run by former Senate majority leader Howard H. Baker (R-Tenn.) had a balance of $575,644 at the end of March.

Another prospective GOP presidential candidate, Marion G. (Pat) Robertson, who has just starting fund-raising for his PAC, the Committee for Freedom, reported a balance of $91,808 at the end of March. Robertson is the head of the Christian Broadcast Network (CBN) and chief host of the network's 700 Club.

Dole and Kemp have been forced by the threat of potential challenges to their congressional seats to divert fund-raising attention from their PACs to their congressional campaigns.

For Dole, this may prove to be a backdoor bonanza if he decides to run for president. Despite early threatened challenges, no serious opposition emerged, and Dole's Senate campaign fund is flush with $1.85 million, separate from the money he raised for his PAC. Depending on Federal Election Commission rulings, the Senate campaign surplus money may be switched to a presidential campaign fund.

Kemp, who has raised more than $1 million for his congressional campaign, does face House opposition and has been forced to spend more than half of his money. As of the end of March, $507,358 was left in his congressional campaign kitty.

While Bush is raking in cash, he is working to defuse criticism that he is amassing a fortune to finance his presidential aspirations. He has been ladling out money to federal, state and local Republicans in a move designed not only to quiet critics but also to win friends among Republicans who are sure to play a major role in the 1988 convention.

This year, Bush gave $282,539 to GOP candidates for the House and Senate, compared to Kemp's $9,830, Dole's $20,000 during the first two months of the year and Baker's $41,497 during the first three months.

John Buckley, a Kemp spokesman, defended the small amount of his direct contributions, contending that Kemp has raised hundreds of thousands of dollars for Republican candidates by appearing at events held in their behalf.

All these PACs supposedly were set up to provide financial support to fellow Republicans, and technically are not to be used as vehicles for presidential campaigns.

In fact, much of the money raised by "multicandidate" PACs is used to finance travel (particularly to such states as Michigan, Iowa and New Hampshire with key primaries), extensive staffs and Washington offices, and receptions at major GOP gatherings.

Over the past year and a quarter, these PACs have given, on average, less than a tenth of what they have raised to Republican federal candidates. During that period, the Bush, Kemp, Dole, Baker and Robertson PACs raised a total of $8.1 million and gave $535,000 to GOP House and Senate candidates.

Baker is the only one of the candidates to set up a formal presidential exploratory committee, which aides say has raised about $150,000. The committee does not have to file with the FEC until Baker announces a formal candidacy.

Of the potential candidates, Dole has just initiated a tactic designed to raise money for Republican Senate candidates.

In addition to his Campaign America, Dole has created a related fund-raising vehicle called the "Majority Leader's Joint Trust." The "trust," in turn, has 16 different subsidiary PACs set up in each of the states where there is an open Senate seat without a Republican incumbent, or where a Democrat is up for election.

Donald J. Devine, who is running Dole's PAC operation, said the trust is raising money for all 16 subsidiary PACs. Once GOP primaries are completed in these 16 states, and the Republican nominee selected, each of the trust PACs will be folded into the nominee's campaign fund in such states as North Carolina, Maryland and California.

Devine contended that using this fund-raising mechanism allows the trust to effectively make unlimited contributions to the Republicans' campaigns. It could not be learned whether such action would meet with FEC approval.