LOL!
The two best were John McCain and Al Gore. I like John McCain, but that was too damned funny.
The two that don’t work are Rumsfeld and Cheney.
You should cast Faramir’s captain, the grizzled warrior who warms him that failure to turn over the Ring to his father will be his death, and the one who dies defending Osgiliath) as Rumsfeld. That works.
For Cheney, the Elf just doesn’t quite work. It’s too bad that Cheney doesn’t look like Gimli. Unfortunately for Cave Man Cheney, Grima really is his image double.