During the 2012 Presidential Election the final national polls (average) had Obama ahead by 1 point. However, a great majority of the state polls had Obama winning every state he won in 2008 except Indiana and North Carolina was a true tossup. My calculation to extrapolate state polls nationally showed Obama had a 5 point lead if was indeed going to carry nearly every battleground state. It certainly made little sense Obama would carry almost every state he won 2008 and only win by 1 point (he won by 7 to 8 points in 2008). Hence, there was a dichotomy between state and national polls. If Obama were to win by 1 point in the popular vote than it would be a close election in the electorate college and the state polls would be wrong. However, if the state polls were right then Obama would in the electoral and popular votes fairly easily – which became the case (won by 4 points). Therefore, we can conclude the national polls were not very accurate.
In the 2014 midterm elections we have a similar situation brewing. The GOP is enjoying a huge margin in the national poll for “Generic Congressional Ballot” – over 3% for the average of polls. This is a huge margin because Republicans are rarely ahead in these polls. This generally indicates a massive tidal wave of seats turning over to the GOP. However, state and local polls do not exactly indicate this type of tidal wave: Governorships look to remain the same or the Democrats can pick up a few seats. The Republicans looked primed to pick up 5 seats in the Senate, but keep in mind there were many more Democrats up for election and many are in red states. And finally, the experts are predicting the Republicans pick up maybe 3 to five seats in the House. This is far from the 65 seats the GOP won in 2010. With a Generic Congressional Ballot lead of 3.5% my models indicate the GOP pick up at least 15 to 17 seats!
If the polls were anything like 2012, then the Generic Congressional Ballot is favoring the GOP by a few more points then what is the true reality and the state and local polls will be more accurate. Time will tell, but national and state polls do not add up again.