With his campaign treasury close to empty and his polls showing him trailing in New England, presidential candidate Edward M. Kennedy (D-Mass.) yesterday canceled all scheduled campaign activities this weekend to reassess the future course of his challenge to President Carter.

Kennedy called off a planned weekend campaign trip to Maine and New Hampshire and announced that he will deliver a "major policy address" in Washington Monday.

But Kennedy, walking through his campaign headquarters here last night to cheer up workers, unequivocally denied suggestions that he might withdraw from the race.

Later, appearing before the Brotherhood of Railway and Airline Clerks, Kennedy gave a forceful, podium-pounding indictment of the Carter administration that did not sound like the talk of a man who has given up.

And he continued to joke about Monday's Iowa caucuses, where Carter beat him, 59 to 31 percent. "Of course I intend to go on," Kennedy told the clerks' union. "Thirty-one percent of the people in Iowa can't be wrong."

Still, yesterday's developments in the Kennedy camp reflect a picture of a confused campaign that faces serious problems:

The accountants have told Kennedy that his campaign has less than $200,000 remaining of the $4 million-plus it has taken in since he announced his candidacy in November.

Campaign workers said that Peter Hart, Kennedy's pollster, finds Kennedy so far behind in New Hampshire that he will have to work furiously to beat Carter in the Feb. 26 primary there.

Press secretary Tom Southwick said most of Kennedy's 200-person campaign staff is now working without pay.

Spokesmen for Kennedy's Illinois campaign announced yesterday that they were shutting down all operations there and that Gerard Dougherty, who was running the Illinois operation, would head for New England this weekend to aid in the effort there.

An hour later, Dougherty was told by Kennedy headquarters in Washington to stay in Illinois and keep the operation going -- but with volunteer staff instead of the 16 paid staff members he had.

Campaign workers yesterday did not try to hide their feeling that things look grim for Kennedy. "We're not concealing the fact that at the moment we're broke," said Rick Stearns, the chief delegate hunter. "We are hunkering down in the trenches."

But Stearns and others said the campaign has begun a nationwide fund-raising effort among true-blue Kennedy supporters and will use the money for campaign workers and media advertising in Maine and New Hampshire.

Although Kennedy is heir to a multimillion-dollar fortune, federal law prohibits him from giving more than $50,000 of his own money to the campaign. His relatives, like other individuals, can give no more than $1,000 each during the primaries.

There was continuing Kennedy activity outside of New England, notably in Florida, where Kennedy is opening two new offices this week.But it is clear that most available money and manpower will be concentrated on Maine and New Hampshire.

Kennedy said this week that he has to win in the Maine town caucuses on Feb. 10 and the New Hampshire primary.

Kennedy's advisers and ghostwriters were mum yesterday about the speech planned for Monday. But by canceling this weekend's campaigning -- in order, Southwick said, to work on Monday's address -- the candidate is likely to draw considerable attention to that speech, just as Carter did last summer when he canceled a scheduled energy speech and spent a week rewriting it.

In the 11 weeks since it began, Kennedy's campaign has received about $3.1 million in contributions and more than $1 million in federal matching funds. But that money has been used up by a candidate and staff who ran a deluxe operation.

Kennedy has hired about 65 people for his Washington headquarters, another 40 advance workers, and roughtly 100 more staffers for local headquarters around the country. The pay has been high, by campaign standards. Kennedy's Senate aides, some of whom were earning salaries above $30,000 in the Senate, say they have been getting about the same pay in the campaign.

At most overnight stops, the campaign has rented more than 20 hotel rooms to house the staff and provide it room to work. Kennedy's charter plane was equipped with telephones, electric typewriters and a videotape machine.

All that is changed now. For his next campaign trip -- when it will be is still not clear -- Kennedy will travel by commercial plane and rented buses with a greatly reduced traveling staff.

Campaign aides are worried about Kennedy's ability to raise money now that the results from Iowa have cast him as a clear underdog, but they are going ahead with some planned fund-raisers.

By canceling this weekend's New England trip, Kennedy will miss a fund-raiser in Providence Saturday night. His sister-in-law, Jacqueline Kennedy Onassis, will pinch-hit for him there.

The campaign staff is still trying to decide whether to go ahead with a scheduled West Coast trip next week, during which Kennedy is to speak at a major fund-raiser in Seattle and smaller events elsewhere.

Kennedy workers from around the country were in Washington Wednesday to figure out how to deal with the new circumstances of underdog candidate and limited budget.

Among the problems discussed was the fact that Kennedy has no TV advertisements made that are designed for a New England audience. Presumably however, he could use TV spots made for his Iowa campaign, because those ads did not have any particular regional flavor.

Southwick said the campaign has already paid for some of the television time it will use in the New Hampshire contest, but that more time will probably be needed. That will now become the campaign's major spending area.

As of yesterday, the termination of payrolls did not seem to be causing a mass desertion of Kennedy campaign workers. The 25 paid workers in New Hampshire all said they would stay on as volunteers, and most of Kennedy's 16 paid workers in Illinois seemed likely to do the same.