Wealthy investor Stephen Pagliuca brushed aside questions about his party loyalty as he announced his Democratic campaign in the special election for the late Edward M. Kennedy’s Massachusetts Senate seat.

In a speech at TD Bank Garden arena in Boston, Pagliuca, managing director of Bain Capital and co-owner of the NBA’s Boston Celtics, promised to honor Kennedy “by making it possible for more of our fellow citizens to realize that American Dream.”

“I’m well aware I’m pursuing the office of the greatest senator in the history of this Commonwealth,” he added. He presumably did not believe the same thing when he and his wife gave $4,000 to Republican Mitt Romney’s unsuccessful 1994 campaign to unseat Kennedy.

“That was a case of friendship coming before politics,” Pagliuca said, noting that Romney “hired me and was the founder of our firm and I worked with him for 20 years.”