American's generally have a two party political system to vote on canidates for office & approving or rejecting laws. They're spin off parties also, but they have never held power. Independents, Libertarians, Green Party, etc. have influenced elections by stealing votes from one of the two major parties. Over the years these spin-offs have allowed the more inferior of the two parties to gain power. The Republican views are generally for "limited government". The Democratic views generally allow more government control to divvy out needs to the people from our collected taxes. People should not become more dependent of the government. Our system isn't perfect but America's Constitution has been the most copied government outline in the world since 1787. A great deal of responsibility is placed on the voters themselves. We must use critical thinking in following our constitutional principles. If we don't stick to our standards, we'll have no standards!
Tend to be liberal policy voters. They are close to the Republican's in commonsense but allow for more change. Inparticularly with social issues. Then we have the harder core groups, Leftists/Progressives which are extremely to the Left, meaning they allow for extreme change,
and would rather not adhere to the Constitution generally, believing it a bit out-dated. Also at this level of voting issues are not so much judged by rule of law but more by rule of man. Thinking more with ones heart than reasoning out issues. Being liberal, they also tend to be a bit louder and aggressive in acting out beliefs. Generally aligned with Socialism.
Example might be groups like "The Occupy Crowd, Trade Unions & Black Lives Matter". No all in these groups are against America's values. But tendency comes within. This can be a rather emotional party.
Tend to be more conserative in voting policies. They are not far off the voting path than Democrat's in terms of commonsense, but they don't support much change in policy. They usually work with the policies already in place and rarely deviate from the constitution's orginal concepts. They can be identified by some form of religion, the NRA and the Tea Party. The formers only goal is adherence to the constitution. But emotional people have unjustifiably made-up other standards to demononize them. Conservatives are generally less emotional and spend more time defending their position then presenting it.