there aren't many liberal republicans left. But I can tell you of Republicans in the past who have been considered such:
Thomas Kuchel (guy who replaced Nixon in the senate)
Lowell Weicker (senator from Connecticut who later became Indy)
Mike Castle At Large Rep from Delaware 1993-2010
Chuck Percy Senator from Illinois 1967-1984
Jim Leach US Rep Eastern Iowa 1977-2006
William Cohen US Senator Maine 1979-1996
Charles Mathias US Senator Maryland 1969-1986
Gilbert Gude MontCo US Rep Maryland 1970s
Connie Morella Same District Rep 1987-2002
Margaret Heckler US Rep Massachusetts 1970s
Ed Brooke US Senator Massachusetts 1967-1978
Marge Roukema US Rep New Jersey 80s and 90s
Clifford Case US Senator from New Jersey 1960s and 1970s
Jacob Javits US Senator New York 1957-1980
Mark Hatfield US Senator Oregon 1967-1996
Arlen Specter US Senator Pennsylvania 1981-2009 (switched parties)
John Heinz US Senator Pennsylvania 1977-1991
Dick Schweiker US Senator Pennsylvania 1969-1980
Hugh Scott US Senator Pennsylvania 1953-1976
John Chaffee US Senator Rhode Island 1977-1999
Lincoln Chaffee US Senator Rhode Island who later became Indy
Jim Jeffords US Senator Vermont 1989-2001 (became Indy)
George Aiken US Senator from Vermont 50s and 60s
You actually forgot Alan Simpson of WY of all places.
