WASHINGTON--Democratic Party officials yesterday predicted a long and hard-fought battle for the party nomination in 1980, while representatives on Capitol Hill predicted that Sen. Edward M. Kennedy (D-Mass.), would easily beat President Carter in such a contest.

John C. White, Democratic Party Chairman and a Carter supporter, said yesterday a Kennedy-Carter matchup would be "one of the classic struggles of our political history."

"If you put the two most powerful figures in America in a contest against each other," White added, "the potential for a bloody mangling nomination process is there."

Speaker of the House Thomas P. O'Neill Jr. (D-Mass.) meanwhile, said a nomination battle could revitalize the party. "The party has always been in the best shape when the arguments and bickering are gotten out of the way the year before presidential elections," O'Neill said.

Meanwhile, Sen. Lowell P. Weicker (R-Conn.) said yesterday Kennedy would easily take the nomination from Carter.

"Kennedy would take it in a walk," Weicker said as he flew to Hartford, Conn. aboard Air Force One as the President's guest. "There's too many Democratic congressmen and senators with their necks on the line. They want the strongest possible person at the top of the ticket," he added.

Carter defended his national health insurance program yesterday at a meeting of senior citizens in Hartford. Kennedy, who was in Washington chairing a Judiciary Committee meeting, repeated his position that "I have not foreclosed the possibility of running."