In a battle between two groups it is rare that the two sides are evenly matched and either give up or declare a tie. It might take a long time to play out, but generally, one side or the other "wins".
Politics are a little different from predation, or from a war, in that everyone is in a broad sense on the same side but on opposing sides in a narrower sense. Deer and mountain lions are part of the same system in a broad sense as well: the elimination of one party would be bad for the other. They counterbalance one another and offer a check on each others' excesses. But as humans, we are (ideally) conscious of our participation in the larger system, and therefore we consciously share some of the same broad goals. Even if we cannot think of a single broad goal we share, we are still in the same bed, so to speak, with mutual responsibility to make it up, and with shared vulnerability to the way in which it is made.
What natural system always trends toward 50/50 results? Well, a coin toss is a good example. If there were something absolute and fundamental about the difference between the parties, a 50/50 balance would not be possible.
I think, rather, the parties represent slightly different approaches to the same problems, magnified many times by sensationalism, and then further magnified by desperation. When one obtains just more than 50% it has its way and runs recklessly in one direction to the dismay and horror of the others, and sometimes to the horror of their constituency. Then it reverses and so on. But the clear implication is that both sides change constantly with time, and the 50/50 balance is a result of their being two sides. If they were not in balance and could not change then a critical outlet for decision would not exist. So, like deer and mountain lions power swings one way and then the other.
But another clear implication is that the content of each side is not fundamentally different but is rather two sides of the same coin. Two approaches based on the same set of cultural assumptions. Even when the cultures appear to be drastically different (as now), there are deeper sets of shared values that guide and shape the apparently different cultures of both sides.
There are very few social circumstances in which I can tell whether someone is "red" or "blue". At work, for instance, I see people doing their jobs, and I might work with someone for a decade or longer and have no idea at all what their party affiliation is. At church, even, my only way of knowing party affiliation is to sneakily watch which car a person gets into and observe their bumper stickers. (I'm sure some churches make better predictors of political affiliation than others but even this is not always the case.) It seems to me that party affiliation has very little bearing on whether one can be a good person, a good citizen, or a good friend.
Both parties have their own claims to the moral high ground. And both parties have moral achilles heels which are are larger than the side of a barn, so to speak. There is no complete guide to truth and goodness that can be harvested from the party lines of one party or another, or even both combined. But political parties are worldly things. They are amalgamations of human ideas, chaotically lumped together into giant seething masses. It is a mob, constructed for better or worse, of people opposed generally to the mob on the other side. People move back and forth constantly, and the party line shifts constantly in response to powerful undercurrents of belief, habit and lifestyle.
If only we could focus on these powerful undercurrents!
I don't want to suggest that we ignore our duty as citizens to participate in a democratic process. I also don't want to suggest that we stop brushing our teeth. These are things we need to do. But the problems expressed through politics are symptoms of deeper issues, and it is those we must address. Focusing on these will make us humbler in the political sphere, it will make us capable of contributing more realistically and less divisively.
Most of all, if we can see our own faults and shortcomings we will be more able to understand the other side, and gradually, hopefully, become able to steer the whole ship, rather than fighting to slam the wheel in one direction or another.