With control of the US Senate up-for-grabs this November, Republicans find themselves five seats away from 50 Senators and six seats shy of gaining a majority.  There’s clearly been a lot of press inside the beltway about this topic recently, including a very cool look at different maps being used to explain the upcoming election by Politico Magazine (http://www.politico.com/magazine/story/2014/05/10-maps-that-explain-the-2014-midterms-106347.html#.U2uccE0o-DY).

But, being a pollster and not a cartographer, I decided to take a closer look at the relationship between the President’s approval rating nationally and his party’s performance in mid-term elections in U.S. Senate races.  As the chart depicts below, looking back at mid-term election years since 1990 suggests that President Obama’s approval rating nationally will be a very strong indicator of Republicans’ chances to win control of the US Senate in 2014:

Since the 1990 mid-terms, when a President’s approval rating falls below 50{09f965da52dc6ab4c1643a77bd40d1f729d807040cd8db540234bb981a782222} (Clinton 1994, Bush 2006, Obama 2010), the President’s party has lost on average 7 seats in the US Senate.

Bottom line – we’re still months from Election Day, but even with a gain of just six seats, as was the case in 2006 for Democrats and 2010 for Republicans, Republicans would take control of the upper chamber heading into 2015.