Though he is generally seen as invincible, Mass. Sen. Edward M. Kennedy '54-56 will face a Republican challenger this fall with strong Harvard ties, sources confirmed yesterday.

Jack E. Robinson III, 39, a Jamaica

Plains multi-millionaire businessman, has decided to seek the Senate seat, held by Kennedy since 1962.

Robinson received a joint degree from the Harvard Law School and Harvard Business School in 1987.

Senior state Republicans describe Robinson, an African-American, as fiscally conservative and socially moderate. He supports abortion rights.

Kennedy's office downplayed the appearance of an opposing candidate--at least until an official announcement has been made.

"Senator Kennedy is not going to speculate on potential candidates," spokesperson Will Keyser said yesterday.

Robinson decided to run after discussions with Michael Sullivan, Plymouth County district attorney, who has long been considered a potential Kennedy opponent. Sullivan decided to drop out of the campaign, after seven months of trying to form a campaign team.