a divided country will never change. It's simple if you think about it. obama slammed the healthcare bill through with hardly more than 50% of the vote. The reason - as a politician pushing an adgenda - you should only shoot for 50% +1 is because you don't need to satisfy (read: 'make concession to') anyone else to get done what you want.
This is voting economics. Just like you wouldn't give a dime more for a car than you need to, someone in the gov't that wants to maximize spending on, let's just say healthcare, only needs approval from 50% +1 vote. If they get anymore approval than that, they are making concession that they don't need to make.
If you have 100 people, each with a $1.00, and you decide as a group that you're all going to 'fairly' redistribute the $ between the 100 of you that you all vote who needs it, you need to buy 51 votes with that $100 dollars. buying any more means you're diluting the benefits.
The two party system thrives on division.