ASHINGTON, Feb. 11 — Census officials plan on Wednesday to announce their estimates of the proportion of the American population that was missed in the 2000 census, as well as the percentage that was counted twice, officials say.

The announcement will help census officials decide whether to recommend statistically adjusting population counts based on data from a sample of American households.

Because the population counts — whether adjusted or not — will be used to draw the districts of the 435 members of the House of Representatives, some politicians say the Census Bureau's decision will have great political significance and may help determine which party will control the House after the 2002 elections.

Under regulations issued by the Clinton administration in October, the head of the Census Bureau — an acting director since the resignation of Kenneth Prewitt as census director last month — will decide after receiving a recommendation from a committee of 12 senior census managers. The committee has met almost daily in recent weeks, poring over data from the actual census, plus the results of the sample of 314,000 households.

Committee members have examined the percentage of census questionnaires that were filled out and returned. They have evaluated the quality of interviews conducted by census takers. They have used sophisticated analyses of how much the census and the sample vary. They have also compared data from both the census and the sample with information gleaned from birth and death records supplied by states, estimates of illegal aliens produced by the Immigration and Naturalization Service and other demographic information.

"For a statistician this is hog heaven," said Howard Hogan, the chief of the Census Bureau's Decennial Statistical Studies Division and a member of the committee.

The committee will make its recommendation by March 1, and the acting director will have five days after that to decide whether any adjustment should be made.

Democrats have been so concerned that the White House will block the Census Bureau from adjusting its data that when President Bush appeared at the House Democrats' retreat last weekend, he was grilled by Representative Carolyn B. Maloney, Democrat of New York, on whether he would allow the scientists at the Census Bureau to decide on adjustment without political interference.

Mr. Bush told the Democrats that he had not been briefed on the issue.

Ari Fleischer, the White House spokesman, was quoted by The Associated Press as saying on Thursday, "The president supports an actual head count, because he believes it's the best and the most accurate way to conduct the census." But Mr. Fleischer said no final decision had been made on whether to allow adjustments to compensate for miscounting.

Even with the political winds blowing around them, some senior officials at the Census Bureau say they are not feeling any pressure as they make their decision.

"What pressure I'm feeling is that I make sure that I'm making a decision that is supported by the data and that when my colleagues in the statistical community look at the data they believe we made the right decision," said John Thompson, the director of the Decennial Census, and a member of the committee.

Census officials have been tight- lipped about what the panel will recommend, though some experts have said they expect it to find that the net undercount in 2000 will be smaller than in 1990, when it was put at about 1.6 percent of the population. The experts suggested that fewer members of minorities, especially Hispanics and to a lesser extent blacks, were missed in 2000 than in 1990.

But both of these trends may be overshadowed by a larger than expected number of people — mainly whites — who were counted twice.

Census officials have been concerned for some time that last year's census may include a large overcount, perhaps even bigger than the more than four million people who were counted twice in 1990. Those who are counted twice tend to be children of divorced parents, college students living away from home whose parents list them on census forms and who also fill out census questionnaires on campus, and people with two homes who have received census forms in the mail at both of their dwellings.

In the 2000 census, officials for the first time made questionnaires available at convenience stores and government agencies and allowed people to provide information over the telephone. The bureau also started an unprecedented $102.8 million prime-time advertising campaign to urge people to fill out the census.

One result of these changes was that the bureau received more than 2.4 million forms that appeared to be duplicates.

Political strategists say any adjustment may benefit Democrats when the boundaries of Congressional districts are redrawn, because it would increase the number of minorities, especially blacks, who tend to live in areas where there is strong support for Democrats, and reduce the number of whites who are more likely to live in areas where voters favor Republicans.