The trailer rented for $7,000 a week. The price didn't include the telephones or the Betamax.

It didn't include the steak tartare, the olives rolled in salami slices or the rosettes of p.at,e squeezed onto little bread rounds -- fare for political Bedouins wandering the concrete desert of Philadelphia's Civic Center in search of their mullah.

"It includes the couches," said an aide to California's Sen. Alan Cranston, 68. He had invited delegates to the Democrats' midterm conference to drop by the trailer, parked in the basement of the hall. "We want them to meet the senator and see a film. A photographer comes in at the end and takes a picture of each of them with the senator. Bang, bang, bang. They get a packet of speeches and articles pertaining to their area of interest -- education, nuclear freeze, whatever -- and out they go, to make way for the next group."

"I'm trying to find out what the reaction is to me," Cranston told a dozen of them, arrayed on the couches. Cranston's familiar bald head gleamed in the trailer's lights, beneath a photograph of him wearing a red-and-blue jogging suit and seated on the Capitol lawn. The delegates seemed slightly puzzled to have the assistant minority leader of the United States Senate seek them out.

"I think it's wide open," he said. "Don't you think so?"

"It" was the Democratic presidential nomination, two years away. Cranston was testing the waters -- a euphemism for running without actually admitting it. During the last six months he had been to 22 states, and would spend the rest of the year -- and some of the $236,000 left over from his 1980 Senate campaign -- traveling to states with early primaries.

Sen. Gary Hart of Colorado and Reubin Askew, the former governor of Florida, were sharing the waters with Cranston. Unlike Walter Mondale and Sens. Ernest Hollings and Ted Kennedy, they had no political action committee (known as a PAC), which is the other way of running for president without having to admit it. Sen. John Glenn of Ohio was planning to form a PAC and in the meantime was traveling the country on funds left over from his previous campaign.

"I find more and more people who think the front-runners won't win," Cranston said, and added, "Hart, Glenn and I are on the second tier."

Some commentators had suggested that he might be on the third tier, that crowded mezzanine of Democratic aspiration where potential vice presidents lurk. But the delegates were too polite to suggest it. They hailed from Kansas, New York, Arizona, Iowa and Ohio, and many wore buttons that read ERA YES/REAGAN NO. They hadn't touched the steak tartare.

"People don't want another outsider for president," Cranston told them. "They want maturity and leadership and proven ability to get things done. I am considering what I could do. I know I'm not the most objective observer, but virtually everywhere I go, except in the home states, it's wide open."

"Senator?" asked a delegate from Kansas.

"Hi."

"As president, what could you do to lower interest rates a goodly amount?"

Cranston criticized deficit spending, then segued easily into nuclear holocaust, a subject that Cranston had been talking about for a long time. "There have been two alerts during which we actually sent planes up and had the missiles ready to fire, all because of the failure of a 42-cent silicon chip . . . Now that I've scared you to death, are there any more questions?"

The aide put his head between orange curtains. "We have a photographer here who would like to take your individual picture with the senator."

As the delegates lined up, an Ohioan inadvertently revealed a MONDALE FOR PRESIDENT button under his jacket. He apologized for it.

"We have a 10-minute film about the senator," said the aide, "made by a volunteer film unit in Hollywood. Right after the pictures."

Three delegates stayed to see the film -- a woman from Phoenix and two Kansans. They heard the theme song from "Chariots of Fire" and a voice: Alan Cranston is one of the best runners in Washington. But the television screen remained dark.

"This is the first time we've tried this," said the aide, glowering at the Betamax.

He started the videotape over again. This time, Cranston was seen jogging through the verdant splendor of southern California, in the same red-and-blue jogging suit. His voice came out of the blue: "I've been running all my life .. ."813 He stopped at different picnics to answer questions about Medicaid, student loans, the arms race.

A woman's voice said, Sen. Cranston, you want to be president, don't you?

Yes.

The film concluded with Cranston churning up a hill and breaking a tape with his chest. He's a winner!

"There are a few rough spots." The aide switched off the machine. "What do you think?"

"It's wide open," said the woman from Phoenix.