If you find any errors in my analysis or have any tips or other interesting pieces of information I'd be really happy to discuss with you.
1. http://en.wikipedia.org/wiki/Left%E2%80%93right_politics#His...
...but if it helps, you made a little English error. Wouldn't even have mentioned if you hadn't said you were French :)
> [Republicans.] Most of which are either moderates or closer to the Democrats than to their own party.
> Olympia Snowe and Susan Collins are the two Republican Senators from Maine which are both regarded to be leading moderates within their party.
Should be "Most of whom..." and "...who are both...".
"Which" is only ever[1] used in relative clauses to describe inanimate objects (as you do correctly five other times in the article). Humans and animals are always either "who" (more personal) or "that" (more impersonal).
Note that's only in relative clauses-- "Which senator is yours?" is fine, but "The senator which represents me" means that I think my senator is a card table.[2]
[1] Outside of the odd dialect, of course.
[2] Not necessarily out of the question.
But as a native speaker "that" sounds slightly more correct than "which" because it seems less formal, however, if I heard a non-native speaker say "which" it wouldn't sound weird nor would it be something I would have corrected them on.
Even so, I wouldn't correct it except that, read uncharitably, referring to a person with an inanimate term could be seen as somewhat insulting. Especially if you're writing about politics, it's probably worth getting right just to avoid that impression.
Using which in a restrictive clause like The senator which represents me... or The road which runs from X to Y... is somewhat uncommon. Both of those examples sound better in American English using that in place of which. If the subjects didn't need disambiguation, though, that would no longer be appropriate, e.g., Senator Jones, who represents me, ... or Foobar Street, which runs from X to Y, ...
As Cushman points out, though, which used on a person doesn't quite work. That can work on a person, though, but who/whom can work for people in both restrictive and non-restrictive clauses.
See http://owl.english.purdue.edu/owl/resource/645/01/ if you want to read a well-structured and thorough explanation.
Which party controlled the Senate that year? It would be interesting to see if switching is correlated to party control. For instance, I see the Republicans controlled the Senate in the 108th (2003-2004).
Dude, check the dates. Two words: Iraq invasion.
Regardless, they might have voted against the operation but then voted for various smaller bills "supporting the troops", which is an entirely reasonable position.
Over time some that voted for invasion adjusted their stance. This may be why you felt there were a lot of opponents.