during discussions about Obama's various negotiations with Congress, you often hear "Read the Constitution! The President can't pass laws!" No, but if the President really wants a law passed, they can do things that aren't in the Constitution, for example:
White House officials insist that they’re confident that a deal will be struck. One top Obama adviser, however, told ABC News that if the House GOP refuses to cut a deal with the president that includes some tax increases on the wealthy, the tax cuts will expire. One scenario the official discussed included the president barn-storming the country, telling the public that Democrats will put forward a bill to restore middle class tax cuts as soon as Congress convenes, and calling on them to pressure Republican congressional leaders to stop holding those tax cuts hostage in exchange for tax cuts for wealthier Americans.
The idea is to get people to pressure their reps and senators to vote in favor of whatever. Dems will do it, since they're already in favor of it. But Republican citizens won't do it, since they are in alignment with what their representatives and senators are doing. That's half the country.
Besides, a few phone calls and emails have virtually no effect on reps and senators. They listen to their big dollar donors the most.