Rep. Morris K. Udall (D-Ariz.) said yesterday he doesn't intend to run for president again in 1980. But he refused to endorse President Carter for the nomination.

Udall said he wants to be a "senior statesman" in the Democratic Party until the early primaries next year when he will endorse someone.

Although he refused to say who that someone might be, Udall gave several strong hints in a breakfast meeting with reporters. If the choice is between President Carter and California Gov. Edmund G. (Jerry) Brown Jr., he said, "I wouldn't have any trouble going with Carter."

But if Sen. Edward M. Kennedy (D-Mass.), whom Udall has known since John F. Kennedy's 1960 presidential bid, gets into the race, the Arizona Democrat may change his position. "It would be very difficult for me to turn my back on those ties, particularly when his [Kennedy's] positions are closer to mine than are Carter's," he said.

If Kennedy wants to be a candidate, he will have to announce sometime between Thanksgiving and early February, Udall said, adding that "Kennedy as an announced candidate has weaknesses that Kennedy as everyone's favorite draft choice doesn't have."

Kennedy's chief weakness, Udall said, is that "the voters are against him on all the issues."

Udall finished a weak second to Carter in balloting at the 1976 Democratic National Convention, and has been mentioned as a possible challenger to Carter next year. Yesterday he all but ruled out that possibility.

The only way he would run, Udall said, would be if "a star from the East settles over my house followed by three wisemen on camels. And the three wisemen would have to be named Cater, Mondale and Kennedy."

Carter should count on some rough sledding in early primaries, especially in New Hampshire, Udall warned."In early primaries, the voters don't pick candidates, they send messages. In New Hampshire, they love surprises."