The sleeper Senate races that may determine whether Democrats or Republicans control the majority

These four Senate races in non-swing states could be pivotal in determining if the Republicans win back the Senate majority in next month's midterm elections

While Trump may not think much of O’Dea, the Senate Leadership Fund, the top pro-Senate Republican super PAC, apparently does. The group, which is aligned with Senate Republican Leader Mitch McConnell, last week funneled $1.25 million to a pro-O’Dea super PAC and said in a statement that it thinks that Bennet is "vulnerable."

While the high-profile Senate showdowns in the battleground states of Pennsylvania, Georgia, Arizona, Nevada, Wisconsin and North Carolina, as well as the expensive faceoffs in competitive states such as Florida, Ohio and New Hampshire have hogged the national political spotlight, the contest in Colorado may be a sleeper in the battle between the Democrats and Republicans for the Senate majority. And the race in Colorado may not be the only contest that could offer a surprise in next month’s midterm elections.