Voters in the District are six weeks from beginning the most thorough makeover of local political leadership since the advent of home rule more than 15 years ago.

Although several of the political contests, notably the races for mayor and congressional delegate, are too close to call before the Sept. 11 primaries, it seems clear that for the first time in a long while, there will be new faces in the most important leadership positions in District government.

Largely because of the domino effect of Mayor Marion Barry's drug arrest and his decision not to seek a fourth term, Washington will start 1991 with its first new mayor in 12 years, its first new House delegate in 19 years and a new chairman of the D.C. Council. In addition, voters will have elected two brand-new shadow U.S. senators and one shadow House representative, all three nonvoting, unsalaried positions.

More important, in the eyes of some of the candidates and independent observers, this may be remembered as the election year when a new generation of younger politicians came into their own, running outside the District's entrenched political establishment and sometimes against it.

"It's time to pass the torch," said Donald M. Temple, 37, a Democratic candidate for delegate who is part of an emerging group of younger city politicians.

There are several indications that voter interest in the race for mayor and other offices is generally low, in part because of the blanket coverage that local media have given to Barry's trial. Polls indicate that a sizable number of voters remain undecided about the election. The candidates themselves also have put off spending money on radio or television commercials until a final, furious push in the three or four weeks before the primaries.

However, registration figures, sometimes an indication of voter interest and possible turnout, are running unusually high this year, according to the D.C. Board of Elections and Ethics. For example, in the first six months of 1986, when Barry was elected to a third term, the elections board recorded 4,643 new registrants, according to spokeswoman Leona Agouridis.

In the same period this year, 24,323 registered to vote.

Agouridis attributed the surge to several factors, including the 1989 law permitting D.C. residents to register at the motor vehicle department when signing up for driver's licenses. Even allowing for the so-called "motor-voter" registrants -- 11,287 of this year's total -- the surge is surprising to election officials.

"It's phenomenal," said Agouridis, who believes registration may reach the high-water mark it normally does in presidential years. The city recorded 5,202 new voters in April, 4,416 in May and 5,578 in June, pushing the total so far this year to 289,153 citywide, just shy of the record 299,757 who registered for the 1988 presidential election. In 1986, there were 273,301 registered to vote in the September primaries.

Registration for the upcoming primaries closes Aug. 13; Agouridis said her office will stay open until midnight that day for last-minute registrations.

Even with a surge in registration, most experts believe the actual turnout in September will be no higher than in recent contested primaries, when 90,000 to 100,000 voters decided the Democratic Party's mayoral nominee.

With that kind of expected turnout, the Democratic mayoral primary -- a crucial election in a city where Republicans are outnumbered 8 to 1 -- may be decided by the candidate who musters as few as 30,000 votes. For instance, David A. Clarke, who is relinquishing his seat as D.C. Council chairman to run for mayor, said in an interview that he is targeting 40,000 voters for primary day, although he expects his actual total may be somewhat less.

In the mayor's race, Clarke is one of three Democratic officeholders who are trying to gain ground against council member John Ray (D-At Large), who is widely regarded as the front-runner. Clarke, council member Charlene Drew Jarvis (Ward 4) and Walter E. Fauntroy, who is giving up his delegate's seat to run for mayor, want essentially the same thing: to cover the distance between them and Ray, while keeping the other two back in the pack.

Local lawyer Sharon Pratt Dixon, making her first bid for elective office, has sought to create her own constituency by casting herself as an outsider to the Barry administration and the rest of D.C. government. Former D.C. police chief Maurice T. Turner Jr. is unopposed in the Republican mayoral primary.

The race for Fauntroy's delegate seat has drawn 10 candidates, seven Democrats and three Republicans. Most analysts say the Democratic primary is too close to call, but D.C. Council member Betty Ann Kane (At Large) and Georgetown University law professor Eleanor Holmes Norton have won most of the endorsements and most of the financial contributions.

Former D.C. Council chairman Sterling Tucker remains competitive in some polls, while former Barry aide Joseph P. Yeldell and Temple, a former congressional aide, appear to be further back.

The general election is Nov. 6.

With a new mayor and council chairman seemingly assured -- John A. Wilson (D-Ward 2) has no strong opposition in his bid to become chairman -- most political activists see some potential for change in the style of the new government, but no major transformation of its day-to-day operations.

"Whoever wins will be facing such massive problems that I don't see any immediate changes," said Lorraine Whitlock, of Northeast Washington, a veteran of several campaigns and a member of the Democratic State Committee from Ward 7. But, she added, "I do hope to see a change in tone. I hope to see more consideration, honesty, integrity. I want to see the involvement of those other than those who have been involved in the past."

The power vacuums created by Barry's arrest and the new seats on Capitol Hill created opportunities for several younger candidates who in another year may not have challenged their political elders.

Some of the younger candidates include Terry Lynch (D), 31, a candidate for an at-large council seat; Harry "Tommy" Thomas Jr. (D), 29, who is running for a shadow Senate seat; and Dee Hunter (D), 25, a new candidate for the shadow House seat.

Temple, a Howard University graduate and a co-founder of a national political action committee to help aspiring black politicians, said the 1990 elections could begin to shift power from a city establishment led by figures from the civil rights movement to up-and-coming black professionals and reformers.

Temple said, "There's a whole new generation of leadership who are beneficiaries of the civil rights movement but who don't have the name recognition of civil rights leaders" such as Barry, Wilson and shadow Senate hopefuls Jesse L. Jackson and James Forman.

"We have the activism of that time, so the struggle now is to move us into the next era of leadership," Temple said.

Temple's inner circle includes veterans of national presidential campaigns, but there is hardly a gray head in the bunch: The campaign manager is 29 years old, the finance committee chairman is 31, the field director is 32, the press secretary is 33 and the treasurer is 34.

"We're not political die-hards, but we are politically sensitive," Temple said. Voters, he added, "are very responsive to the theme that it's time for a change, it's time for a new generation to have the opportunity to serve."