JUST A COUPLE of more shoes remain to be dropped in the Democratic presidential race. Six candidates are in; a number of possible others are out. Jesse Jackson, who announced his 1984 candidacy on "60 Minutes," went on "Good Morning America" Monday to say that he'll announce his 1988 candidacy Oct. 10. It would shock observers inside and outside the Beltway if Mr. Jackson should say he's not running. So the only suspense -- aside from speculation that one of the noncandidates will get into the race -- is about the intentions of Patricia Schroeder. Will she become the eighth candidate in the Democratic field?

That will depend, she said when she first started thinking about running this June, on how much money she can raise. She got pledges of $350,000 at the NOW convention in July and has solicited some big contributors, but like many politicians today is relying primarily on direct mail. The initial response, according to her direct-mail consultant, Roger Craver, is encouraging: test mailings of various lists have brought in $4 for every $1 the mailing cost. That's an excellent response rate for a presidential candidate and, if it can be sustained, indicates that she can raise the kind of money -- several million dollars -- the other Democratic contenders have.

But there may be a catch. "There is often," cautions Mr. Craver, "an inverse relationship between what happens in the mails and what happens in campaigns." The things that attract a few hundred thousand contributors can repel tens of millions of voters. Both parties depend on contributors whose motivations are ideological and whose issue positions are often out of line with those a steely-eyed adviser looking to the general election would prefer. The competition between them depends on which party can produce a nominee who can win maximum support from narrow activist constituencies with minimum damage to his appeal to the broad but not easily mobilized general electorate.

Since the demise of professional, patronage-oriented politicians some time in the 1960s and the rise of direct-mail politics in the 1970s, this competition has been won mostly by the Republicans. They have a larger contributor base and seem to depend less on inflamed appeals to activists, yet raise more money: by June 30 the five Republicans who are accepting federal matching funds (Pat Robertson isn't) raised a total of $19.7 million, compared with $13.9 million total for the six declared Democrats. Rep. Schroeder has been able to generate enthusiastic support from feminists and others who admire her work in the House and on the Armed Services Committee for 15 years. Between now and Sept. 29, when she is expected to announce her intentions, she must decide whether Mr. Craver's "inverse relationship" applies or whether she can translate that into a candidacy capable of winning 2,081 votes in Atlanta and 270 votes in the electoral college.