Bush threatens to veto bill. Why?

Can anyone help me with this? Last November the American voters made it as clear as it coud be that we wanted the Democrats to do something about the war. They did! They worked and introduced a bill for the war and our troops and now the president said he will veto it. What was the point of us putting the Dems in there if what they say doesn't matter anyway? Bush isn't the king, but a man who is president. Why do they even bother if they know what they say means nothing? What the heck is the purpose of our Congress and Senate anyway if they cannot help us? It almost sounds like a dictatorship. Personally, I think the people need more power. Any thoughts?