Suggestions by @lennoxtanderson

Rowan Atkinson

as Neville Chamberlain in Prime Ministers of the UK

Score: +2

Billy Connolly

as Ramsay MacDonald in Prime Ministers of the UK

Score: +1

Oliver Parker

as Stanley Baldwin in Prime Ministers of the UK

Score: +1

Martin Sheen

as Andrew Bonar Law in Prime Ministers of the UK

Score: +1

Paul Giamatti

as John Adams in The Presidents

Score: +1

Donald Petrie

as Donald Trump in The Presidents

Score: +1

Robert Downey Jr.

as Barack Obama in The Presidents

Score: -1

Chevy Chase

as George W. Bush in The Presidents

Score: +1

Stephen Fry

as Bill Clinton in The Presidents

Score: +1

David Koepp

as George Bush in The Presidents

Score: +1

Pierce Brosnan

as Ronald Reagan in The Presidents

Score: +1

Michael Shannon

as Jimmy Carter in The Presidents

Score: +1

Bruce Willis

as Gerald Ford in The Presidents

Score: +1

Joe Mantegna

as Richard Nixon in The Presidents

Score: +1

Michael Gambon

as Lyndon B. Johnson in The Presidents

Score: +1

William H. Macy

as John F. Kennedy in The Presidents

Score: +1

Alan Arkin

as Dwight D. Eisenhower in The Presidents

Score: +1

Charles Dance

as John Quincy Adams in The Presidents

Score: +1

Jean-Hugues Anglade

as James Monroe in The Presidents

Score: +1

Eminem

as James Madison in The Presidents

Score: 0