I have a question about the noun "balance" here:
2014 Senate Balance of Power
Does "balance" here mean a specified state of equilibrium?
The Balance of Power refers to some measure of difference between the majority and minority political parties. In the US Senate, the difference is 6. If the Republicans gain 6 seats, the Balance of Power swings to them. If the Democrats maintain a majority, the Balance of Power stays "dipped" on their side.
Yes, though equilibrium and balance, in this context, do not necessarily imply equal or static power distribution. At the time of publishing, the document aims to show how the Democratic and Republican parties measure up to one another, as if putting both on an old fashioned set of swing scales.