Republicans' strong showing in Senate elections on Tuesday will not only allow President Trump to appoint a flood of conservative judges over the next two years, it will likely put a Senate majority out of reach for Democrats in 2020. This means that even if a Democratic candidate defeats Trump, it will be impossible to enact a sweeping liberal agenda. Though all usual caveats apply about how a lot can change in two years, here's the uphill battle facing Democrats. Right now, Republicans will enter the next Congress with at least 53 seats and probably 54 given that Martha McSally's...