Charlie Cook: “With 25 Democratic Senate seats up next year, ten in states Trump carried, five in states the former real estate developer won by 19 points or more, this should be a year for the GOP to expand its current narrow 52-48 majority. Under different circumstances, the GOP could hope to boost their Senate numbers by four to seven seats, perhaps even reaching the magic 60-seat Senate super-majority level that could break filibusters on party line votes.