Basketball star Tom McMillen announced today he is ending his career with the Washington Bullets and running for U.S. Congress in Maryland's 4th District. McMillen said he will leave the team next spring and run as a Democrat for the House seat being vacated by retiring Rep. Marjorie Holt, a Republican.

The 1986 election in the 4th District, which includes all of Anne Arundel County, a large swath of southern Prince George's and part of Howard County, is likely to attract great attention as Democrats -- who far outnumber registered Republicans in the area -- try to gain control of the seat held by the popular Holt since 1973.

McMillen, the only declared Democratic candidate, is a former Rhodes scholar, relatively new to the district and the world of elective politics. So far, the only declared Republican candidate is Anne Arundel native Del. Robert R. Neall of Davidsonville, the well-liked House of Delegates minority leader.

Speaking at Anne Arundel Community College yesterday morning, McMillen stressed his ties to the area and the need for a strong military defense -- an apparent effort to counter criticisms from some local politicians that he is a newcomer to the area and to politics and a liberal as well. He was flanked by Sen. Paul S. Sarbanes (D-Md.) and State Comptroller Louis L. Goldstein, both of whom pledged their support.

"I am a resident of Maryland by choice, not by chance," the tall, silver-haired McMillen said yesterday. He noted that he attended the University of Maryland, runs two small businesses in the Crofton area, and that even while he played on basketball teams around the country, "my home and friends were here in Anne Arundel County."

Since moving to Crofton three years ago, McMillen, 33, has been making the political rounds throughout the 4th District, attending party functions, bull roasts and club meetings. He has attracted the admiration of some party officials, the suspicion of others.

State Del. Gary Alexander (D-Prince George's), who is chairman of the Democratic Central Committee in Prince George's, said McMillen gives Democrats "a real shot at capturing the 4th District."

"There's a good feeling between him and the people," Alexander said. "It's not like he's some Rhodes scholar in an ivory tower. He comes across as a regular guy."

State Sen. Thomas V. Mike Miller Jr., (D-Prince George's) called McMillen "a very attractive candidate," saying, "He's got the look of the candidate, apparently the brains to have the job. He's got the ability to raise the money."

But some of the "old line" Anne Arundel politicians have "not warmed up to his candidacy," Miller noted, and McMillen will have to work hard to overcome that.

One Anne Arundel Democrat contemplating running for the 4th District seat is state Sen. Gerald W. Winegrad (D-Annapolis). Winegrad said he has recently been consulting Democratic leaders -- and Tom McMillen -- about seeking the seat himself. "I'd have no qualms whatsoever about supporting Tom," Winegrad said yesterday, but added he was worried McMillen can't get enough support to beat the Republicans.

"Some people feel that Tom hasn't paid his dues, hasn't been involved in the issues," Winegrad said. "I think that's the biggest criticism -- that he just doesn't have the roots. It's not that he hasn't lived here long enough. Everyone else has worked their way up from being involved in community affairs, from being activists. They see his involvement as just in running for Congress."

Anne Arundel County Executive James Lighthizer, a Democrat, said a race between McMillen and Neall would be "a tough, close race." Working against McMillen will be his lack of experience in area politics, he said, adding, "The good news is that he's got a high profile."