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.

Democrats consider the senate seat a safe bet, but Kennedy is taking the campaign seriously.

He faced a strong challenge in 1994 from businessman Mitt Romney, who waged a $7 million campaign. Romney spent $3 million of his own money.

To prevent a repeat of the near-disastrous campaign, Kennedy has built a $3.6 million campaign fund--the largest he has had going into a campaign.

Robinson, if he decides to run, will receive the maximum amount from the Republican National Senatorial Committee: $650,000.

Coupled with the million dollars Robinson has pledged to spend, he would have half of Kennedy's war chest--without working to raise a dollar.

Robinson earned his fortune by helping to design a cellular telephone network in the Caribbean. He has not lived or worked in Massachusetts for years, but has voted here recently. Alumni directories list his address as New York City. He claims a residence in Greenwich, Conn.

The Massachusetts Democratic Party seized on the issue.

"The Republican Party in this state has reached a new level of desperation," Executive Director Mark White told the Associated Press. "If their best bet now is to Fed-Ex a candidate from Connecticut, they are in real trouble."

Now entering his fourth decade in the U.S. Senate, Kennedy welcomes the chance to discuss issues important to Mass. voters.

"He's looking forward to the upcoming campaign," Keyser said.

If the Democrats take control of the Senate, and Kennedy is reelected to a seventh term in the Senate, he will become chair of the Committee on Health, Education, Labor and Pensions.