How much can one representative do? I think you're overstating his power. He is one of 435, and while he does have influence over the law in the fact that he can vote against it, I don't think one representative has the power to completely block a bill if he doesn't have people standing behind him.

The best way to get other representatives to stand behind him is 1. passionate appeals on the House floor and 2. getting voters to make their voice heard.