I see that you have listed only Senators. It is a good idea to call and let them know your displeasure about this, but not quite panic time.
If the Senate passes this bill, then the House will also have to pass the bill. Then a Conference Committee will have to meet to make both bills exactly the same!! At which time, both the Senate and the House will again have to pass the bill, before it can go to Dubya to be signed into law.
All of this will have to take place before adjournment for elections. If this bill is passed by the Senate, there is still time to launch a well thought out campaign.