The Post's editorial on the mayor's race has helped turn what had been a difficult choice for most voters into an agonizingly tough one.

A vast majority of the voters in the District clearly want a change from Walter Washington. That is their starting point, as it has been The Post's.

As the voters choose up sides between Marion Barry and me, however, the dilemma and irony become obvious. If Marion and I evenly split the vote of all those who want a change, Walter Washington will be reelected - the very result The Post, the voters, Marion and I all want least.

So the time has come for the voters to make a truly tough decision: Should they ask themselves only which of us they prefer? Or should they ask themselves also which of the two acceptable alternatives to Walter Washington has a chance to beat Walter Washington?

The Post's poll suggests that the Post's editorial went to a candidate with only a slim chance to win. The Post's poll (and our own) shows this as a very close race between the mayor and me, with Marion doing better than expected but still trailing by a wide margin.

Obviously, I think the Post editorial came to the wrong conclusion. I personally do not believe that Marion's style and background are as well suited to the demands of the job as my own.

My style and background are more one of "creative leadership and management" - stressing the need to get people working together, concentrating on sound planning and professional administration and solid organization, focusing on dramatic change through a unity of purpose and long, tough, day-to-day work. It's how we won home rule. It's how the Urban League won 75,000 new black job opportunities for the District in the days of segregation. It's how the City Council has been able to function without a single congressional veto since home rule. I believe it is the way to turn city hall around now, to provide the tax relief and jobs and housing and education we need - the new day of hope our city so desperately needs.

Marion's style is obviously more flamboyant. He has battered on the structure doors - and has won some important achievements. I don't personally believe, however, that that style will work very well in the mayor's office, where the trusting cooperation of public employees, Capitol Hill, the business community and so many others is so essential to turn hopes into reality.

But my point is not to quibble either with The Post's editorial or with the equally sincere judgment of voters who would prefer Barry to Tucker. Rather, my point is to ask us all to remember where we started on this race, the thing we all agree on: The 10 tired years of Walter Washington must end on Tuesday.

That won't happen if all those who want it to happen split their votes between Marion and me. So the time has come to make the hard choice - to put change before anything else and go with Tucker, because he can win.

Marion Barry has run a stronger Campaign than I expected. The Post's editorial attests to its impact. So far I honestly believe the city is better off for his running. I know his effort has forced me to sharpen my own stands on some issues. But it will all be for naught if votes for him allow Walter Washington to win. If that happens our city won't be better off; it will be a disaster.

Four more years of Walter Washington will mean four more years of his tired team. It will mean four more years without planning and management and hope. It will mean four more years without jobs for our youngsters and homes for our disadvantaged and meaningful tax relief for overburdened property owners.

I'm not a miracle worker. And I'm not going to promise the sky. But I do promise a new spirit in city hall, new blood at the top and in the departments, a new effort to attract jobs, a new surge to solve the housing shortage, a new priority to reach national norms in our schools.

I promise a new day for this city. That's what I believe most voters in the nation's capital want above all. And if we stick together on Tuesday, that's exactly what we can have.