The national leadership staff of Citizens for America, a conservative group headed by drugstore magnate Lewis Lehrman, was fired or prompted to resign last week amid charges of mismanaged funds.

Lehrman sped from political obscurity to national prominence, particularly among conservatives, with his surprisingly effective 1982 gubernatorial campaign against Democrat Mario M. Cuomo in New York, which Lehrman lost by a margin of 2 percentage points. Since then Lehrman has used Citizens for America (CFA) largely as a personal vehicle to keep his name and trademark red suspenders in the political spotlight.

According to Lehrman's friends, he still has political ambitions and is considering challenging Cuomo next year if the governor seeks reelection and a national campaign in 1988. One of those fired last week from CFA said the organization was "gutted." But Lehrman said in a telephone interview that he remains "very optimistic" about the organization's future.

Last week seven members of the CFA national staff were fired or quit. Apparently, Lehrman concluded that the organization's $3 million budget was being mishandled, although he declined to comment on the reasons for the shakeup. (In the previous six months, more than half the staff of 40 had left the organization, CFA sources said.)

Lehrman has not been closely involved in the group's day-to-day activities. Instead, he has raised money and traveled.

In early June, Lehrman went to Angola, where CFA staged a conference featuring four anticommunist guerrilla movements. There he gave framed copies of the Declaration of Independence to Afghan, Laotian, Nicaraguan and Angolan rebels.

When he returned, he discovered that he was "boxed out of the bookkeeping" of CFA, according to one of his personal aides. He sent in his private lawyer. "It was one big party," Lehrman's aide said. Jack Abramoff, executive director of CFA, and other members of the staff Abramoff had hired "had gone hog wild," Lehrman's aide -- who declined to be identified -- said.

The financial "mismanagement" and "lavish spending," the Lehrman aide said, is still being untangled.

On July 15, Abramoff resigned. All those staff members associated with him no longer are associated with CFA. Abramoff could not be reached for comment. Grover Norquist, the former CFA national field director, is in South Africa, according to a CFA spokesman. Peter Willett, the former CFA comptroller, said, "Everything from my end is off the record."

"As a result of circumstances," Lehrman said, "the opportunity arose to undertake reorganization . . . . We have a streamlined operation . . . . The present organization is exactly what we need to complete the job."

The group's plan was to organize chapters in each congressional district and lobby for President Reagan's program.