Jesse Jackson's presidential campaign has been paying Richard G. Hatcher at the rate of $70,000 a year to work as national director at a time when Hatcher has also been serving the final months of his fifth term as the full-time mayor of Gary, Ind.

The campaign consulting-fee arrangement -- unusual for an elected official, though not illegal -- came to light in a campaign-spending report Jackson filed this week with the Federal Election Commission.

It showed that from mid-May through Sept. 30 of this year, Hatcher received $2,916 twice a month in consulting fees and an additional $2,000 a month in expense allowances.

Hatcher, 53, one of the nation's longest-serving mayors, defended the arrangement in an interview yesterday, noting that there is nothing in local or state regulations to prevent him from taking outside compensation. "I am worth every dollar I receive," he added.

On May 5, Hatcher was defeated in a Democratic primary in his bid for a sixth term. His term expires Dec. 31. He said he has continued to work "full time" at his $52,497-a-year city hall job, explaining that he has been spending nights and "an average of one to three days a week," most of them on weekends, working on the Jackson campaign.

When Hatcher served as Jackson's campaign chairman in 1984, he worked without compensation -- the usual arrangement for elected officials who take part in a presidential campaign. This year, his title is national director and chief executive officer, and he says his role has been "very hands-on."

Hatcher is by far the best paid staffer on what is the least-well-funded of the six Democratic campaigns for president. The FEC reports show that the campaign chief of staff, Yolanda Caraway, is receving $1,418 bimonthly and the director of communications, Frank Watkins, is getting $1,075 bimonthy.

Other presidential campaigns on the Democratic and Republican side pay their top staffers salaries or fees ranging from about $5,000 to $10,000 a month. In some of the financially strapped campaigns -- especially that of Rep. Jack Kemp (R-N.Y.) -- the top campaign brass have worked for considerably less. Top Kemp campaign directors, Edward J. Rollins and Charles Black have been working without compensation.

Hatcher, a lawyer and city councilman before he became mayor 20 years ago, said he will work full time for Jackson when he leaves office. This past March, during his campaign for a sixth term, it was reported that he owes $20,923 in back taxes and penalties on a 31-unit vacant apartment building.

One of Hatcher's chores as campaign director has been to head a search for a full-time campaign manager. The Jackson campaign is the only one with that position unfilled.

According to several sources, Jackson has been turned down by several people with national campaign experience.

Hatcher said he expects to hire a manager within weeks.