The Economy - Stock Prices

What has caused the stock markets to rally? Is the economy doing better? Is Ebola not a problem anymore? Are companies doing better and better? I don't think so, so why is the market up? I think it is in anticipation of the Republicans winning big in the upcoming election. If the Republicans take over the Senate, then things will probably be more positive for business and stocks in particular. But what will a Republican Congress get done? Will it be able to override a veto? Probably not, so a Republican win is a step in the right direction, but I don't imagine much happening. What will the markets do when they figure that out?