The federal and most state governments are dominated by two political parties: the Republicans and the Democrats. There are many smaller parties; the largest of these are the Libertarian Party and the Green Party. People help in political campaigns that they like. They try to persuade politicians to help them; this is called lobbying. All Americans are allowed to do these things, but some have and spend more money than others, or in other ways do more in politics. Some people think this is a problem, and lobby for rules to be made to change it.