Local or community politicians often seek office because they want to make changes or improve where they live in some way.
Those seeking state office may still want to improve their state but many also are eyeing the national spotlight such as being a congressman, U.S. Senator or even president.
At this level ego plays a large part in the decision to run as well as being backed by rich and powerful people who hope to be able to count on the candidate to support the things that are important to them.
Most candidates for U.S. Senator or president are millionaires or have reached financial success. Their goal now is to create a legacy by entering into the chambers of power. It has been predicted that over $1 Billion dollars will be raised by each party's (final nominee) for the 2016 presidential race. The second half of their first term is spent raising money and support to get re-elected.
The end result of each presidential election is having half the nation disappointed that (their candidate) didn't win. The role of the opposition party becomes finding ways to stifle the sitting president in hopes of getting their candidate elected in the next election.
In today's political climate "compromise" is seen as weakness or being a traitor and may even cost an elected person support from their own party. They want to avoid giving the other party any "victories" that might cause the public to re-elect the person they want to replace. Gridlock is built into the system.
What is best for the party is more important than what's best for the nation if one wants to hold onto to the support of their party.
Once you figure this out you know the game is for candidates to make a ton of promises of which are impossible for them to keep without getting congress to pass legislation.
This rarely happens unless the vast majority of the congress is in the same party of the elected president.
The only exception to gridlock is when poll numbers indicate the vast majority of people in the nation are in favor of something.
Politics today is simply another sport where people cheer for their team and sling mud at the opposing team on a daily basis.