Now it's your turn to help fill in some of the remaining gaps or make alternate suggestions. Central Casting is always looking for ideas, so even if someone's penciled in for a role, we'll bump them if you come up with a better fit. (And if you think someone's missing from the script entirely, add 'em in.)

However, there are two rules:

1. You can't re-use actors from Primary Colors in the same roles, so no John Travolta as Bill, Emma Thompson as Hillary, etc.
   
2. No "joke" suggestions ("Jabba as Mark Penn!"). I've heard them all before, and we'll never make our release date if we just clown around here, people.

So here goes (and I apologize that the picture formatting makes the diary stretch out a while)...

Hillary Clinton: Sharon Stone or Susan Sarandon (gchaucer's recommendation)
Bill Clinton: Warren Beatty (not a lookalike, but Beatty's got starpower befitting a president.) . Another suggestion for Bill was David Morse
Chelsea Clinton: Alison Lohman
Barack Obama: Will Smith (again, it's about the starpower. We need to sell tickets!)
Now, if we're not concerned with box-office (maybe we're aiming for that artsy Sundance vibe?), then we could use Harry Lennix instead .  Even less-known but most closely resembling Obama is Scott Lawrence.
Michelle Obama: Kimberly Elise
John McCain: Richard Dreyfus
Cindy McCain: Joan Allen
Howard Dean: Mark Harmon
George W. Bush: Chris Cooper
Mark Penn: Edward Herrmann
David Axelrod: Jeffrey Tambor (not sure about this one, but there's not many balding guys with mustaches I can think of)
John Edwards: Bill Paxton (he even sounds just like him)
Mitt Romney: Bruce Campbell
Bill Richardson: Graham Greene
Rudy Giuliani: Joe Pantoliano
Mike Huckabee: Kevin Spacey
Ron Paul: John Mahoney (a.k.a. Frasier's dad)
Joe Biden: ???
Fred Thompson: Kelsey Grammar (with makeup)
Chris Dodd: Peter Gallagher (with makeup and silver wig)
Mike Gravel: Harve Presnell (of Fargo fame; w/o mustache)
Dennis Kucinich: ???
Duncan Hunter, Jim Gilmore, Tommy Thompson, Sam Brownback: Just cast some extras. No one cared about these guys even when they were running.
Tom Tancredo: Harvey Keitel (no one cared about him, either, but at least he was nuts, and nuts makes for good cinema)
Geraldine Ferrarro: Lee Meriwether
Jeremiah Wright: Walter Mosley (the author; this may be cheating, but he looks more like Wright than any actor I could think of)
Ed Rendell: Jon Polito (sounds like him, too; w/o mustache)
Chris Matthews: Philip Seymour Hoffman (thanks to RigsoHC)
Tim Russert: Brendan Gleeson
Keith Olberman: John Larroquette (though he's considerably older)