District of Columbia Democrats will caucus Saturday to choose the slates of delegates who will appear on the ballot in the May 6 presidential primary. That contest is expected to be an early measure of black support for President Carter or Sen. Edward M. Kennedy.

The two four-hour causes will be political insiders' affairs. With less than two percent of the city's 188,000 registered Democrats expected to take part, the caucuses are not nearly as much of an indicator of voter sentiment as the well publicized caucuses of Iowa and Maine.

Still, the line-up of would-be delegates pledges to support each of the four major candidates is one of the first indications of how the campaign may be fought here, and organizers for President Carter say they see some symbolic value in Saturday's meetings.

"It's important that we show our numbers," said Janette Hoston Harris, coordinator of Carter's Washington campaign. "I'm not looking at this as a victory. . . . We have to generate spirit."

Political organizers for all major candidates hope to develop a slate dominated by well known names and by persons with active political followings.

In the days leading up to the May 6 voting and on election day itself, campaign organizers expect these household names to translate into more workers, more money and eventually more votes for their candidates.

"A good slate is a one you can take to any community and win with, said Anita D. Bonds, Washington campaign coordinator for Kennedy. "You also want people who have a track record. You've got to have some constituency."

Based on the number of elected officials and other political well-knowns pledged to support various candidates, Carter appears to be strongest in the high-voting neighborhoods of Wards 4, 5 and 7 -- stretching from the eastern edge of Rock Creek Park to the fringe of Anacostia.

Among those supporting him there are City Council members Charlene Drew Jarvis (Ward 4), William R. Spaulding (Ward 5), and Willie J. Hardy (Ward 7), Bishop Smallwood E. Williams of Bible Way Church, former Council Chairman Sterling Tucker, D.C. School Board Vice President Barbara Lett Simmons and public housing activist Kimi Grey.

Carter is also strong in Ward 3, the mostly white and affluent section of the city west of Rock Creek Park. There his supporters include Council member Polly Shackleton (who is not running as a delegate), businessman John W. Hechinger and State Democratic Chairman Robert B. Washington Jr.

Kennedy appears strongest in the transitional inner city areas -- Ward 1, 2 and 6, where young middle class whites who are renovating old homes are emerging as a political force. Voters in these areas were a major factor in Marion Barry's surprise victory in the 1978 Democratic primary for mayor. i

In these areas, Kennedy has the support of Council members David A. Clarke (Ward 1), Nadine R. Winter (Ward 6), John Ray (At-Large) and Betty Ann Kane (At-Large). Also among those running to represent Kennedy as delegates are the Rev. David H. Eaton of All Souls Unitarian Church, gay activists Melvin Boozer and Paul Kuntzler, restaurateur Stuart J. Long, Peter Schott of Americans for Democratic Action, and William H. Simons, president of the Washington Teachers Union.

D.C. Del. Walter E. Fauntroy is running as a would-be Kennedy delegate in the area that includes the vote-rich, heavily black neighborhoods where Carter appears strongest.

Mayor Marion Barry and City Council Chairman Arrington Dixon have both endorsed Carter, but are not running as a would-be Kennedy delegate. Both are expected to be added to the delegation later, when six discretionary delegate posts are filled by the D.C. Democratic State Committee and the delegates chosen May 6.

The caucuses are not just a personality parade, however.They are also a chance for various special interest groups in the city to begin shoring up slots in the delegation that will allow them to wield influence when the presidential nominee and party platform are chosen at the national convention.

Any Democrat is eligible to participate in the caucuses. The city has been divided into two "districts" -- District 1, including Wards 1, 2, 6 and 8, will hold its caucus at Georgetown University Law Center, 600 New Jersey Ave. NW; while District 2, made up of Wards 3, 4, 5 and 7, will hold its caucus at Dunbar Senior High School, 1301 New Jersey Ave. NW. h

Both meetings will take place from 11 a.m. to 3 p.m., and caucus officials caution Democrats to arrive early -- doors open at 9:30 a.m. -- to have their names checked against registration lists.

Delegate candidates are either uncommitted or pledged to support one of the declared candidates -- Carter, Kennedy, Edmund G. (Jerry) Brown Jr. or Lyndon H. LaRouche Jr.

The city's 13 elected delegate seats will subsequently be doled out to each candidate according to how much of the popular vote he receives in the May 6 primary.