WASHINGTON -- A population explosion among the nation's racial and ethnic minorities -- particularly Hispanics -- is expected to raise significantly the number of Hispanics and blacks in the House of Representatives. The question is: By how much?
The number ultimately will be determined by redistricting, which is the uncertain art -- part statistical, part political -- of reshaping the nation's congressional districts, based on the 1990 census.
Early last week, some analysts reluctantly offered rough, please-don't-pin-me-down estimates of the impact of the massive growth in the nation's non-white minorities on their representation in the House. They estimated the additional numbers of Hispanic-majority and black-majority congressional districts likely to be produced by redistricting.
Then, assuming that with rare exceptions these so-called "minority districts" are and will be represented in the House by minority members, the analysts found:
* The number of "Hispanic" seats in the House may nearly double, from 10 now to at least 18, and possibly 20, after the 1992 elections.
* The number of "black" seats is likely to show an increase of about a third, from 24 now to 32 after 1992. The analysts noted that two or three districts that previously have had black majorities may be at risk because of blacks' out-migration from cities to the suburbs and their replacement by an influx of Hispanics.
* Asian-Americans -- with Hispanics, the other minority that experienced the largest growth over the last decade -- now occupy three seats in the House, but their number is not likely to increase through redistricting, the analysts said. Asian-Americans, according to the analysts, are too scattered throughout the nation at this time for the construction of an "Asian" district.
* One American Indian, representing the nation's oldest but smallest non-white minorities, sits in the House now. No change is expected.
As if to validate the analysts' reluctance to offer confident estimates, the Census Bureau released data Thursday that cast some doubt on its count.
The agency announced that in a survey to determine the accuracy of last year's census, it discovered that as many as 6 million people -- including 2 million, or 5.6 percent, of the nation's blacks and 1.8 million, or 6.1 percent, of its Hispanics -- had not been counted by the census takers.
Two major black and Hispanic organizations, the National Association for the Advancement of Colored People and the National Council of La Raza, responded immediately by calling on the Commerce Department, as they have in the past, to adjust the census results statistically to compensate for its under-count of minorities.
The survey revealing the under-count "confirms what we believed all along -- that the census process is flawed," said one of the analysts, Clifford Collins, a redistricting specialist with the NAACP.
Lisa Navarrete, spokeswoman for La Raza, said the survey's indication that the census under-counted minorities "doesn't surprise us a bit."
A federal court has ordered Commerce Secretary Robert A. Mosbacher to decide by July 15 whether the census should be statistically adjusted to make up for the under-count.
Mr. Mosbacher has indicated in the past an unwillingness to make the adjustment. The NAACP and La Raza are engaged in lawsuits aimed at forcing the commerce secretary to adjust the census.
The two major political parties held divergent views about the survey and the issue of whether the census should be adjusted.
Gary Koops, a spokesman for the Republican National Committee, described the survey results as "preliminary numbers," and said the question of adjusting the census was one the committee would deal with "down the road."
Ron H. Brown, chairman of the Democratic National Committee, held a meeting with civil rights and voting rights advocates Friday, after which he said: "The 1990 census has been a disgrace. It is the most inaccurate in 20 years, particularly in its under-count of blacks and Hispanics."
Mr. Brown said he was "not optimistic" that Mr. Mosbacher would order an adjustment of the census results, which the Democratic chairman and most members of his party have advocated.
On the basis of analysts' estimates, non-white racial and ethnic minorities are likely to occupy about 55, or 13 percent, of the seats in the House after 1992.
That, however, would represent only about half of the proportion non-whites in the nation's population. Americans of African, Hispanic and Asian descent now constitute between one-fifth and one-fourth of the U.S. population. Hispanics may designate themselves racially as either black or white.
Because of the underrepresentation of minorities in the House, federal laws -- the Voting Rights Act and past court decisions -- demand that the first priority of redistricting be the creation, wherever possible, of minority districts.
However, adherence to the minority-district principle has led to skirmishes in which the district maps are on the table, the computers are busy clicking out various redistricting scenarios, and the political knives are drawn.
In some places -- Texas and California, for example -- black and Hispanic interests are colliding.
And in other areas, House incumbents, white and black, are fighting for their political lives: Chicago, Detroit and, closer to home, s Prince George's County.
A heavy migration of blacks into Prince George's County has caused black political leaders there to press for the creation of a minority district within the county.
That possibility, however, could threaten the political future of one or the other of the two Democratic incumbents whose districts currently include sections of the county -- Representative Tom McMillen, D-4, and Representative Steny H. Hoyer, D-5.