They currently control 49. Joe Manchin is retiring, so West Virginia will likely put their total at 50.

Republicans have additional pickup opportunities in [related markets linked - but note that they DO NOT ALL have the same resolution criteria]

Meanwhile, Democrats have basically no pickup opportunities. Their best options are Texas (Ted Cruz 

Anyway, I wanted to make a granular market on number of seats, because I’m curious about stats like the median, mode, and “are Republicans more likely to win 55 seats than to lose.”

I will resolve this market once each Senate race is projected by a major news network or Dave Wasserman. I will re-resolve if these projections turn out wrong, or if there is a surprise party switch. 

General policy for my markets: In the rare event of a conflict between my resolution criteria and the agreed-upon common-sense spirit of the market, I may resolve it according to the market's spirit or N/A, probably after discussion.