If their constituencies were writing them letters informing them that they had better grant amnesty or else, they would be singing a different tune. That isn’t the nature of the letters that they’re getting however. I think the Democrats are divided now that they have all seen how Obama’s immigration game is developing.
I wonder about constituent letters, based on my own experience. I just about never communicate with my Senators and Representatives, because they’re liberal, and I feel like I’d just be wasting my time. I think they’d only react if contributors were bitching, not constituents at large.