The National Association of Realtors Political Action Committee gave $5.8 million to congressional candidates in the past five elections, and has already handed out $875,000 for this year's contests, according to a report recently released by Common Cause.

RPAC has contributed more than $3 million since 1979, sometimes supporting opposing candidates in the same race, and today 88 percent of all current House members and 87 percent of all current senators have received some funds from the group, the self-styled citizens lobby said.

"If you exclude the local affiliates of the American Medical Association, then Realtors are No. 1 in campaign contributions," said Randy D. Huwa, the lobbyist for Common Cause who wrote the report. "They were ninth in 1974 and have risen to be No. 1 for the past three years."

Bill Adkinson, spokesman for the National Association of Realtors, said this week that PAC contributions come from association members but do not come out of their dues. He said approximately 109,000 of the association's 600,000 members contribute to the PAC fund, averaging $35 per Realtor per year.

"This is a real grass-roots organization, not a few rich people giving a lot of money," he said.

The Realtors rate each candidate and contribute from $100 to the maximum allowable $10,000 to the campaigns of those who support legislation that promotes homeownership and investment, said Jack Carlson, executive officer of the association.

"Those particular objectives are for the common good, not just for the good of Realtors," he said.

According to the Common Cause report, there were 43 instances of Realtors contributing money to both the Republican and Democratic candidates for the same House seat in the 1981-82 elections. There were 42 instances of the same double contributions in Senate races from 1977 to the current election cycle.

Also, the study found three instances in which Realtors contributed money to a losing candidate, then turned around and gave money to the candidate who won after the election was over.

"No doubt they are covering all bets in an attempt to be as influential as possible," said Common Cause's Huwa. "PAC money does gain access to the members. That is not to say PACs always win, but they are always heard."

Realtor spokesmen said they have contributed money to opposing candidates because members on a local level have split over whom they wish to support. They also said that if both candidates have good Realtor "report cards," the PAC may decide to contribute to both.

"Sometimes we have . . . sat back and let whomever wins win, if both candidates are acceptable," said Carlson. "Or we contribute to both, or to one after the election."

Most local representatives in the Washington area have received PAC money, with Virginia Republican Reps. Frank R. Wolf receiving $15,000 and Stanford E. (Stan) Parris $15,200 from 1979 to June 1984. Parris' total was the highest of any area legislator.

"PAC money absolutely has no impact on the representative," Syd Courson, a spokesman for Parris, said last week. "Congressman Parris is not unsupportive of development as long as it does not fly in the face of public good. Development is a major issue in his Fairfax County district. Therefore, it is not surprising they Realtors would support us."

Democratic Rep. Michael D. Barnes, whose district includes most of Montgomery County, was one of the few local representatives who has not received any Realtor money since 1979.

"We do accept PAC money, and we received contributions from local real estate agents during our last campaign," said his press secretary, Bill Bronrott. "I have no idea why the Realtor PAC did not support us, but it makes no difference to his stand on issues."

Virginia Republican Sens. Paul S. Trible Jr. and John W. Warner received $5,500 and $7,000, respectively, from Realtors since 1979. Maryland Sens. Paul S. Sarbanes, a Democrat, and Charles McC. Mathias, a Republican, received $1,250 and $1,000, respectively.

According to the report, the Realtors also have contributed $217,000 to the Republican Party and $213,000 to the Democratic Party in the past five years.

The PAC has contributed $30,000 in the past five years to Rep. John Edward Porter (R-Ill.), the most any single legislator received. Huwa said Porter was in a special election for his seat, which may explain why he received extra funds.

Generally, members of House and Senate committees that deal with real estate and finance were more heavily funded than legislators on other committees, Huwa said, adding, "It is clear they want their influence spread well."

The National Association of Realtors most recently has been involved in legislation dealing with the federal deficit, government spending and tax policies, Huwa said. This year the PAC has lobbied strongly against provisions in recent tax bills that would restrict tax advantages for homeowners and real estate investors.

"It is anyone's guess as to how much we influence Congress," said Carlson. "But our PAC gives local businessmen, Realtors, the opportunity to get involved in government on local and national levels. That is the most important aspect of it."