The Republican party and Democratic party are not two separate parties. They only appear to be. The social network that ties the two together are tightly connected. Their core agenda is the same. They merely put on different facades to entice people into attacking each other rather than fighting against their tyranny.
We can start by looking at the Obama administration and comparing it to the Bush administration. The main flaws with the Obama administration are that it mirrors and expands upon Bush's, including endless warfare. We can also look at PPACA or so called "ObamaCare" which is largely based off of RomneyCare. That itself was constructed with the help of Ted Kennedy, who Romney called it's "parent". Ted was also a "good friend" of Romney, again highlighting the social connection between these "two" parties.