What can we realistically do to affect the outcome?Right Wing News has some ideas, and also nails down the Republican presidential candidates' positions (who may have more influence with their peers than most)
PS #2: I have checked the websites of the candidates to see if they have released statements on the bill. To the best of my knowledge, here's the current breakdown on the Senate Amnesty Bill (if you have confirmation of where any of the "unknown" candidates have come down, please let me know in the comments section)In addition to posting, let's try some letter-writing, phoning, and faxing (email is the LEAST influential - it takes the least effort, and costs nothing - the other options have more impact). Target each of the above for some contact.
Ron Paul (I would think he's opposed, but can't verify)
Also, write to your local newspaper, urging action. Write to the local TV station. Heck, hit the national media outlets, as well. The more, the merrier. Each time you do, give anyone reading it some options (email addresses, phone numbers, etc.) for action.
Don't forget your email list. If I can fairly judge by by contacts, people are VERY angry about illegal aliens invading their country.