So, a guy--let's call him presidential candidate Shucks--makes promises he's making and then if he keeps them, the only places to get the money from is

1) the American people
2) special interest groups, whom we know have the population's best interests at heart

So, Shucks gets elected. Guess where the payback will come from? The special interest groups have already paid once, so Shucks will turn to that never-ending supply of cash, the American people.