Updated: 4:32 p.m.Paul Kirk, a former aide and close confidant to the late Sen. Edward Kennedy (D-Mass.), was sworn in Friday as a temporary replacement for his old boss, who passed away Aug. 25. With Kennedy’s surviving children, wife and former staff members looking on, Kirk enjoyed a warm reception on the Senate floor. Speaker Nancy Pelosi (D-Calif.) and Rep. Patrick Kennedy (D-R.I.), the late Senator’s youngest son, each wore bittersweet expressions as Kirk, most recently the chairman of the board of directors of the John F. Kennedy Library Foundation, was sworn in by Vice President Joseph Biden. Kirk, 71, was tapped Thursday by Massachusetts Gov. Deval Patrick (D) to serve until a Jan. 19 special election determines a permanent Kennedy replacement. His swift installation brings Senate Democrats back to a filibuster-proof 60-member caucus that leaders hope to hold together to pass a sweeping health care reform bill this year. Kennedy dubbed health care reform the mission of his public life, and Kirk is unlikely to stray from his former boss’ priorities on that issue. A former chairman of the Democratic National Committee and the political director of Kennedy’s failed 1980 presidential campaign, Kirk is now the sixth appointed Member to join the chamber this year. The most recent new Member was Sen. George LeMieux (R-Fla.), who was sworn in Sept. 10 to serve the final 16 months of former Sen. Mel Martinez’s term.