When Lew Wasserman comes to town, it's not just as the chairman of the Music Corporation of America, which runs a conglomeration of entertainment enterprises including the Universal universe and the Tourmobiles on the Mall.

Wasserman also comes as a Democrat of long service. And at yesterday's Kennedy Center reception honoring him for his gift of $100,000 to equip and furnish the Center's new library, Wasserman spent much of his time huddled in serious conversation with White House communications assistant Gerald Rafshoon.

Robert Strauss joined the conversation at one point with the word that Sen. Edward M. Kennedy would not challenge President Carter for his job. Kennedy told House speaker Tip O'Neil, who told Strauss, according to Strauss.

Later Wasserman was asked about the chances of his fellow Californian Jerry Brown against the president. He Made no predictions, but he made it clear that "I have already made a moderate contribution to the Carter-Mondale campaign."

Not all of the chat was about politics, however. Rashoon talked about the recent screening of Francis Ford Coppola's "Apocalypse Now" at the White House. He said the war scenes were good, but he had reservations about the rest of it. The President saw it, but Rafshoon wouldn't say what he thought.

Asked whether Coppola's big Vietnam movie might affect Universal's "The Deer Hunter," Wasserman said he didn't think so. "Francis deserves a hit," he added.

Meanwhile, he predicted that Steve Martin's "The Jerk" will be "the biggest success of the year." It happens to be a Universal picture.