Two years from the start of the 2000 Census, it is shaping up as the most contentious in 80 years, generating a firestorm of debate and strategizing in Congress and litigation aimed at blocking the Census Bureau from changing the way it does business.

Congress has ordered the traditionally apolitical Census Bureau to draft two plans for conducting the census - one the old way and one using a proposed new method, statistical sampling, which is at the center of the dispute.At issue is the Census Bureau's plan to forgo its traditional method of trying to physically count every person in the country. Instead, the bureau proposes to try to count all the people in 90 percent of the households in each census tract, which is a geographical area consisting of about 1,700 dwellings.

Using those figures, bureau statisticians would try to determine the number of people in the tract who had not been physically counted. The bureau would then check for accuracy by conducting a survey of 750,000 households nationwide and making any needed adjustments to the final total.

The statistical sampling plan was prompted by the 1990 census, which missed 10 million people and double-counted 6 million, according to census studies.

Most Republicans vigorously oppose sampling, arguing that it violates the Constitution, which calls for an "actual enumeration" every 10 years. But the proposal is staunchly supported by many Democrats who assert that it is the only way to get an accurate tally of minorities - particularly inner-city blacks and Hispanic migrant workers.

Beneath these assertions lies a raw political fight that is based on race and redistricting. Sampling may increase the count of minorities, primarily blacks who are the Democrats' most loyal voters, in some congressional and state legislative districts. Since these districts tend to be safe ones for Democrats, boundaries could be redrawn by legislatures to shift some of the "surplus" black voters into neighboring white districts, making these districts more competitive for the Democrats.

"The Republicans are very much aware of this," said one Democratic redistricting expert. "That's why they're fighting it. They're scared they're going to lose the House."