President Clinton plans to nominate congressional staffer Laura S. Unger and White House lobbyist Paul R. Carey to the Securities and Exchange Commission, federal and congressional officials said. Unger is a securities aide to Senate Banking Committee Chairman Alfonse M. D'Amato (R-N.Y.). Carey, son of former New York Gov. Hugh Carey, raised funds in the state for Clinton during his 1992 presidential bid. Associates describe Unger and Carey as middle-of-the-road pragmatists. Clinton plans to announce the appointments when Congress returns after Labor Day. The appointments of Unger, 36, and Carey, 34, will give the SEC a full complement of five commissioners for the first time since November 1994. "They'd both be fine candidates," said SEC Chairman Arthur Levitt, who added that he has not yet been informed of the nominations by White House officials. Both Unger and Carey have "professionalism and a commitment to the public interest," Levitt said. Neither candidate could be reached for comment. White House officials declined comment on the appointments. The appointments will require Senate confirmation.