With a $1,000-a-person cocktail party at Ethel Kennedy's McLean, Va., home, presidential candidate Edward M. Kennedy last night successfully completed a week-long cross-country campaign blitz aimed at a politically potent subculture; the liberal rich.

From the gilded elegance of New York's Hotel Pierre, where the chauffeured limousines circle the block and the check room was turned into a sea of mink, to the faded splendor of the Hollywood Palladium, where the tuxedoes were brown, silver and blue and every third dress had a shocking neckline, Kennedy entertained his well-to-do supporters with appeals for compassion for the downtrodden.

Kenndey held fund-raisers in eight cities, taking in just under $2.5 million for his campaign treasury and bringing his total campaign receipts to about $3 million, according to campaign manager Stephen Smith.

For what its worth, this means the Kennedy campaign raised more in its first seven weeks than President Carter's campaign committee took in in its first seven months.

Next month, the federal government will give the campaign $1 million or so in matching funds. This means that financially, at least, Kennedy probably will be equipped for a protected battle with his rival for the Democratic presidental nomination.

Kennedy took a break from raising funds last week to address the United Mine Workers' convention in Denver. The miners stomped and cheered when Kennedy called for a federal health insurance plan and condemned Carter for asking people to pay more for oil products. "You know who that hurts most," he roared. "The people who can least afford to pay."

But the miners were not the only people who applauded those lines. At all the high-ticket dinners and cocktail parties, Kennedy's message was the same and the audience responded with almost the same enthusiasm.

The lawyers, businessmen, entertainers and real estate titans who paid between $100 (Chicago) and $1,000 (New York and Washington) each to hear Kennedy cheered lustily when Kennedy complained that Carter had abandoned the Democratic Party's concern for the poor, the elderly and the unemployed.

Kennedy's audience in St. Louis, a handsomely dressed group that paid $500 each for brunch with the candidate, gave him his loudest applause when called for national health insurance. The $500-a-plate diners in Miami broke into applause when he called for more federal help for inner city youth.

Kennedy's wife, Joan, in her first extended campaign trip, joined him at the fund-raisers in Miami and Boston. She looked healthy and happy. His sister-in-law, Jacqueline Kennedy Onasis, was present in New York and St. Louis.

The candidate, who has lost his lead in the polls and his image in the political community as a sure winner, seemed tired and occassionally testy during the frenetic week.

For the most part, though, he retained his sense of humor. Each time Kennedy made a slip of the tongue, the traveling press corps would take over the campaign plane's public address system on the next flight and play back the blooper over and over. Kennedy laughed as loudly as anyone.

When Kennedy was explaining in a television interview his charge that Carter had made a deal with Republicans over a defense spending bill, he said that strong circumstantial evidence supported the charge. "If it looks like a duck, walks like a duck and quacks like a duck, it's a duck," he said.

At that points the interview ended and the lights and microphones were turned off. The senior senator from Massachusetts then turned to the reporter, flapped his arms in a wing-like manner and quacked three times. CAPTION: Picture, Jacqueline Kennedy Onassis joined the candidate in St. Louis for a $1,000-a-couple brunch that also was attended by St. Louis Cardinal greats Stan Musial, left, with wife Lillian, and Lou Brock, with wife Virgie. UPI