Why does it have to be blue vs. red?

Whatever happened to meeting in the middle on political issues? I am old enough to remember when American politicians were generally more moderate, not so partisan and seemingly unwilling to compromise as they have been recently. "Working across the aisle" sounds great in speeches but it is not being practiced by a majority of elected lawmakers and other officials. Why can't we have a legitimate third party that has some real support and influence. I believe that a majority of Americans would place themselves in the middle third of the political spectrum and we are not being represented accordingly.