The sunset is scheduled for September. The election is in November. A failure to sunset just two months before the election will be easily remembered. They know that.
The keys are letters to the newly seated Congress, and getting the 95% of gun owners for whom even writing a letter is too much work to do even that for once. GOA style postcards won't do; they're thrown away by the truckload. We've got to have real letters, with stamps and signatures, steadily showing up in Congressional offices between January 2003 and November 2004.
Be polite, point out that there's no "assault weapon" crime problem, and urge them to let the ban expire as scheduled. Electoral threats of "I'm never voting for you!" sound childish and don't become gun owners. We're responsible, pleasant people, great next-door neighbors, right?
Those who write now that we're doomed, the ban will be renewed, are being defeatist. It'll be a self-fulfilling prophecy if we heed them. We put pro-gun people into office this last election through our hard work. Let's keep it up and made sure this ban goes away - if it stays, then we will have only ourselves to blame.