When Clarence Thomas, the blunt but often beleaguered chairman of the Equal Employment Opportunity Commission, walked down the stairs of a Capitol Hill restaurant on Saturday, about 50 friends, staff and supporters burst into a hearty chorus of "For He's a Jolly Good Fellow."

"I didn't know I had so many friends," he told the crowd, surprised, as he laughed loudly and bit his nails during the remarks of William Bradford Reynolds, assistant attorney general for civil rights; Clarence Pendleton Jr., chairman of the U.S. Civil Rights Commission; Samuel Cornelius, a special assistant to Agriculture Secretary John Block; Billy Joe DuPree, a former Dallas Cowboy and now president of a Dallas construction company; and Sara O'Meara, founder of a national child abuse organization.

Thomas is only one of the new breed of black Republicans and Reagan appointees who have been the target of criticism from liberal Congressmen, leaders of traditional civil rights groups, and others who feel they are turning back progress in civil rights.

"Survival," said Thomas when asked about some of the highlights of his tenure. "I think people have been brutal. They've been hostile, people ignore you and the only thing you can hope when you walk into a room is that they do ignore you."

But Woodson, Pendleton, presidential assistant Melvin Bradley and party stalwart LeGree Daniels, and others at two events Saturday, said they were not leading a retreat but trying to encourage new thinking. And sometimes simply stirring up a storm with their own remarks about black leaders' "bitching," which Thomas said, or how black leaders were leading blacks into a "political Jonestown," which Pendleton said.

When Bob Woodson walked into the gala Saturday night of the National Black Republican Council -- one of five major, and sold out, black Republican events -- several people stopped to deliver a back-slapping welcome of "good work."

Woodson, president of the National Center for Neighborhood Enteprise, last week had arranged a meeting between President Reagan and a new bipartisan group, the Council for a Black Economic Agenda. "I have been getting calls from blacks from all over the country every five minutes," said Woodson. "They applauded the new thinking and expressed concern about the attacks from the civil rights leadership about our right to speak."

The Woodson meeting and the president's remarks three days later that some black leaders were ignoring the accomplishments of his administration in order to "protect some rather good positions that they have," gave an added sense of momentum to Saturday's party -- and some felt credibility for their cause.

"For two years I have been talking about the closed mind of black leadership, the president just backed us up," said attorney Clarence McKee, who headed the District's Republican delegation to the convention. Like many others, McKee sees the poverty and joblessness of many blacks as a continuing problem, not only a Reagan problem.

"One-point-five million blacks got jobs in the last 18 months," said McKee. "We have always had the employment gap. We have also been behind in college boards, and teen-age pregnancy didn't happen in the last four years."

"Well, the black Republicans have to grow," said George Brown, the former lieutenant governor of Colorado and a Democrat, who was at the party. "They have seen so little in the past."

When singer Jeffrey Osborne urged his audience of 2,000 to join him by teasing, "I know the Republicans can outsing the Democrats," the response was loud and harmonious. Housing and Urban Development Secretary Samuel Pierce walked around the boxes and tables, shaking hands, leisurely posing for pictures. Joseph Coors, the president of Adolph Coors Co., which underwrote some of the entertainment expenses, said of the new black Republican power: "I think an awful lot of blacks would get involved, if it weren't for the traditional black leadership. The president will get into trouble for his remarks but he hit the nail on the head."

Even those not familiar with Washington politics felt the black Republicans were on the crest of a new movement. Lorenza Butler Jr., a 24-year-old president of a wholesale business in Houston, said the young black Republicans were not moving away from civil rights concerns. "In business, you give to social issues, such as the United Negro College Fund. Young black Republicans are looking for the same opportunities as the young white Republican. The bottom line is success now."