Decentralization and Party Politcs

In the United States we think of party politics as being 2 main parties, but it is so much more. There are so many different views a person can have, and it is nearly impossible for each person to be completely represented. People are different all across the country, have their own opinions, and what this does is decentralize these parties, and almost creates completely different parties. What this then leads to is members of a given party being less loyal to a major party, therefore making that party less effective. With less effectiveness each party will struggle to strive towards their goals, and much of the agenda will not be met all because the party is not strong enough. So with people crossing party lines and not fully backing those people of their party they have weakened their party, and left them struggling. President Obama pushing for this "reaching across the isle", party politics lose what they have stood for, and lose the loyalty of their members. So many people are praising those who crossover the party lines and join with a new party, but is that what their voters really wanted them to do. Many times if you voted for somebody you have voted for their party as much as the person, and expect them to back their party and remain loyal to that party. Throughout the entire process of the previous election we heard about bipartisanship, and how important it would be in the coming years to get things accomplished. But where does it leave the party in that situation? Parties are left useless when crossing the isle occurs, which makes me wonder who the leaders of the parties are, and what are their jobs.
Here is the link that i posted earlier in the post. It talks about how people are excited that republicans are backing the stimulus plan, and praises them from crossing over, but where does it leave the rest of their party, that which they were elected because of. http://www.foxnews.com/politics/first100days/2009/02/08/liberal-group-praises-crossover-republicans-minority-leaders-balk-partisanship/