True democracy would require national leaders in government to represent the sentiments and feelings of people of their district or State. The two party system however turns candidates into national politicians who represent the views of that particular party more than the local interests.
Once that becomes a reality, politicians cannot claim that their main interests are primarily to serve the concerns of those who elected them. The politicians' interest become more nationalized.
They may then only want to appear to serve those who elected them primarily for political purposes. Voters are not necessarily interested in re-electing representatives unless the voters are more interested in their national political party goals.
As leaders get re-elected they gain more national authority and power and some gain wealth. Generally the longer they remain in power, the more they are likely to remain in serving their own interests and become less the citizens serving temporary role of representing their constituencies.
Now added to that is the lobbyist. The lobbyist is someone who may have been a politician and is now paid to represent the special interest of a particular group or groups and who has the ability then to gain access to the politician even more than one of the citizens who elected the politician.
Lobbyist access is usually regular and in various ways and it is for the purpose of influencing the politician in taking action in the interest of those represented by the lobbyist. This may or may not be in the interest of those who voted for their representative.
Funds for election campaigns enter the picture as well.
It becomes apparent that once elected, the politician gains power unto herself or himself, that may not represent the voter's interests completely or even in part.
Longterm politicians are more likely to become powers unto themselves and now, therefore we have created the professional politician who aims at making his/her position a long term occupation.
Those few who remain or become independent are more likely to serve their constituencies because they have no loyalty to a particular party. Although to remain effective, they are usually required to either lean toward one of the parties or to work more closely with one than the other.
Some politicians attain appointed positions in government which moves them further toward a nationalized role.
Therefore, democracies that aim to function as governments representative of the people, in this example, the people of the United States, the representative aspect loses out. Politicians usually then become the leaders of their own interests and ideas and attempt selling them to those who elect them.
This may no longer require an appearance of representation and voters may then tend also to associate themselves with national party interests and make their interests those of the party as well. Therefore, governors for example bring those national party interest into State politics.
Because they blatantly serve their party interests, governors tend to become the pool of presidential candidates quite removed from their roles as local representatives.
Democracy is quite fragile to begin with and has been turned into representative-type government to function at all. But even government that tends to represent the people usually best represents on a national level of political thinking. Therefore, a citizen's interest can be best served through party affiliation.
So politically, people are either Republicans or Democrats and usually in opposition to each other.
Both usually cannot then be represented by the one elected official. He or she is more likely to be loyal to those of her/his party. So that's the way it is. And there you have it up to this point. More later.