The year 2014 is the last time that the Republicans have an opportunity to gain control of the US Senate, having lost it in 2006, and failing to regain it in 2008, 2010, and 2012.
Nate Silver believes that the GOP MIGHT gain control of six seats needed to make a majority, but does not predict more than that!
The reason for that is that the Democrats have to defend 21 seats, while the Republicans only have 15 seats to defend, all due to the good Democratic year of 2008, when Barack Obama helped to keep a Democratic majority in the Senate, at the time of his first election.
But in 2016, the Senate will have only 10 Democratic seats facing election, while the Republicans will have 24, and that guarantees that, even if the Republicans gain a slight majority and control in 2014, that they will lose it for sure in 2016, with a strong Democratic Presidential nominee and the Electoral College greatly favoring the Democrats for the White House.
But do not assume that the Democrats will actually lose six seats, and realize that ObamaCare will become a popular and positive move in the coming months, with over 6 million now covered by it, and many former critics, who had listened to GOP propaganda and right wing talk show hosts, realizing how good a plan it really is, and a true life saver for millions!
And If Barack Obama can have some luck and skill in foreign affairs over the next seven months, as with possible resolution of the Ukraine crisis with Russia, then all bets are off on the GOP gaining the Senate in 2014.
But again, even if they do, the GOP will NOT have control for more than two years, and 2016 will see a major Democratic resurgence in the upper chamber!