Fred Thompson just entered the race but is already a co-frontrunner in the national polls for the Republican nomination. President Picker still thinks that Mitt Romney will leap past both of these candidates after the Iowa and New Hampshire primaries in which Romney is doing very well thanks to a very aggressive campaign in those states.
That said, Thompson is clearly representing traditional Republican values where Giuliani sports a powerful "new Republican" message. It's going to be a fun race to watch.