Democrats believe they have a real chance at flipping four states Trump won by double digits

For weeks, top Democrats in Washington have watched with cautious restraint as Republicans dumped millions into red states like Kansas and South Carolina to defend an increasingly shaky Senate map.

​ For weeks, top Democrats in Washington have watched with cautious restraint as Republicans dumped millions into red states like Kansas and South Carolina to defend an increasingly shaky Senate map. Read More Breaking News, Latest News and Videos | CNN