Just a bit of advice from back when I was sending letters over the DMCA.

If your congressman is supporting the bill, don't bother. My Senator at the time was Fritz Hollings; came from a poor district, so he was dependent on a lot of outside contributions. I recall Disney being one of his largest contributors. I received a response 3 months after it passed that more or less told me I was a enemy of commerce. I won't lie, I was a little shocked to get back such a pointed letter when I was as courteous and respectful as possible.

I learned my lesson from that one. You can send a letter to anyone and generally it is a great idea, but if they get a dime from your position's opposition, it is just pissing in the wind. It's just business.