Most of the time, when the Kennedy press bus pulls up at a campaign stop and its bedraggled denizens troop out toting their note pads, cameras, and assorted electronic gadgetry, nobody in the crowd even notices -- the attention is focused instead on Edward M. Kennedy himself.

But for a brief spell today the press bus equaled the candidate as the center of fascination. For today, the nondescript unknowns who populate the Kennedy press corps were joined by a natty looking, gray-haired gentleman who is, according to opinion polls, as famous as and more trusted than any politician in America.

Grown men gaped and women squealed with recognition when they spotted Walter Cronkite's familiar face. Shouts of "That's the way it is" rang out by the dozens when he walked into the "press pen" at the Kennedy rally at Mercyhurst College here, and before long the school band was chanting his name to the beat of a booming bass drum: "Wal-TER! Wal-TER!"

Cronkite left his CBS anchor booth to join Kennedy, and, later, Vice President Mondale on a clear, balmy campaign day to report what his producer called "your basic Pennsylvania overview story."

The CBS star, an engaging 63-year-old who is known at his network as "Uncle Walter" and who does seem like your favorite uncle, did his best to ignore the cheers and the pleas for autographs so that he could fit in with the rest of the press and do his job. But it was not to be.

For one thing, the rest of the press was clearly excited to have the profession's most prominent member along. The traveling reporters, who have divided political journalists into two categories -- junior reporters, known as "little feet," and senior political analysts, or "big feet" -- have given Cronkite a designation all his own: "Ultra Foot." The impending arrival of "Ultra Foot" himself was the talk of the bus for two days.

For another, Cronkite was the only reporter in memory who had his own advance team, just like the politicians. A researcher and a producer showed up on the Kennedy bus Saturday -- in addition to the CBS correspondent, producer, and camera crews regularly assigned -- to gather information for Cronkite's use.

Wherever he went today, it was clear that Cronkite was not just another reporter.

While Cronkite was interviewing Kennedy in Pittsburgh this morning, a local TV reporter and crew camped out in the hallway, waiting to interview Cronkite.

When Cronkite forsook his chartered Learjet to fly on Kennedy's campaign plane, the stewardess, who normally serves Kennedy first and then takes orders from other passengers, served Cronkite, then Kennedy, and then took orders from others.

Still, Cronkite's producer lamented that Ultra Foot couldn't get anything more out of the candidate than all the other reporters had been getting. In the Pittsburgh interview, Kennedy turned all of Cronkite's questions around to his favorite issue -- the economy -- and talked about that no matter what he was asked.

Cronkite seemed to admire Kennedy's skill at the tactic -- so much so that he adopted it himself shortly afterward. The local TV reporter interviewing Cronkite asked hostile questions about the power of the media.

With a quite smile at Kennedy, Cronkite responded to each question by saying, "Well, the economy is the number one issue."