Atlanta Mayor Andrew Young is suffering from the "Jesse Jackson syndrome," which is causing many black politicians to pause and withhold their public endorsement of the announced Democratic presidential candidates until Jackson decides whether or not he, too, will run.

Young says he probably would have endorsed former vice president Walter F. Mondale by now, but he says the possibility that Jackson might seek the Democratic nomination has so excited blacks that he and other black politicians have decided that it is better to be safe than sorry.

The Atlanta mayor says he isn't sure the Jackson syndrome is good because it has halted the entire campaign and kept discussion of issues by blacks from developing normally.

Jackson's possible candidacy already has changed the face of the presidential campaign, according to the announced candidates' advisers. To several, the Jackson syndrome is a blessing.

"Jesse's possible entry into the race has forestalled the automatic black endorsement of Mondale," said Charles H. Smith, deputy political director for Sen. John Glenn (D-Ohio). "It's bought time, and we're appreciative of that."

The announced candidates already are paying more attention to issues affecting blacks, although it's still inadequate, critics say.

Each has publicly endorsed the idea of a black presidential candidate and held open the possibility of a black running mate. Increased black voter registration and voter participation have become the motherhood and apple pie of this Democratic campaign.

George Dalley, Mondale's deputy campaign manager, does not concede that Jackson has slowed endorsements for Mondale.

"Jesse's a good place for black politicians who don't want a commitment at this point to rest until they really see if we can win it," Dalley said last week.

When he runs into opposition to Mondale based on Jackson, Dalley said, he tells people that Jackson has no prospect of winning because Jackson has done little to really develop the "Rainbow Coalition" on which he says his candidacy would be based.

Dalley also says that in pragmatic political terms, Jackson can do little more than criticize Reagan, while Mondale has a good civil rights record and can be more effective.

"The appeal can be made," Dalley said, "that we are the candidacy capable of carrying the black agenda, winning the nomination and defeating Ronald Reagan. Jesse's candidacy only carries one of these."

Black support is crucial to Mondale in the South, where there are several early crucial primaries and caucuses.

Glenn's strategists, while not conceding the black vote in the South, see Jackson's southern strength as a benefit to Glenn because in many areas they say he is the most popular among whites.

"We don't need 50 percent of the black vote to win in the South," said Smith.

Glenn has less name recognition among blacks than Mondale. The pause imposed by Jackson's possible candidacy has given Glenn time to break down his conservative image with small, face-to-face appearances at such gatherings as the NAACP National Convention and the Congressional Black Caucus legislative weekend.

Glenn was warmly applauded at the caucus weekend when he urged Senate approval of a bill making the birthday of the Rev. Martin Luther King Jr. a national holiday, assured the audience he would name numerous blacks to his administration and called on the country to commit itself to increasing literacy and raising student scores on standardized tests.

"It's not just the nomination this summer," he reminded the audience as he closed. "We've got to keep in mind who can win in 1984."

That is the same argument used by organizers for Sen. Gary Hart (D-Colo.). Robert B. Washington Jr., former District of Columbia chairman and an adviser to Hart, says Jackson is able to spur the registration of blacks as Democrats, heighten black enthusiasm and to force discussion of black issues that might otherwise be ignored.

"The flip side of that," Washington said, "is that he generates issues that people have to take stands on in the primary that make them unelectable in the general."

Washington said he also fears Jackson's voter registration efforts may be nullified if his effort gives blacks false hope of capturing the nomination and blacks stay home on election day in disillusionment.

Strategists for Sen. Alan Cranston (D-Calif.) say they cannot approach blacks with the idea that Jackson's candidacy is hopeless.

"That's the same argument that they use against us, that we can't win," said Cranston campaign aide Ronald Weathersby.

In two southern states, the Jackson syndrome is compounded by the fact that former governors with significant black support are seeking the nomination.

In Florida, a key state with an early primary, Jackson's candidacy could hurt Mondale and others more than former governor Reubin Askew because Askew has black support based on his liberal record as governor, according to Washington lawyer James L. Hudson, an Askew adviser.

Prominent black Democrats in South Carolina say that the influence of Sen. Ernest F. Hollings in state party politics and Hollings' record are likely to minimize his delegate losses.

Former senator George McGovern of South Dakota, the most recent entry in the Democratic race, said he saw no conflict between his candidacy and Jackson's because both were in the race to "sharpen the issues."

Meanwhile yesterday, Jackson was granted an indefinite leave of absence, effective Friday, from Operation PUSH (People United to Serve Humanity), a Chicago-based civil rights organization he formed in 1971.