One of the outstanding questions left in this election is whether the Democrats' ground operation – an operation that has proven to be far superior to that of Republicans in recent years - will be enough to help their candidates squeak out narrow victories. Thus far, Democratic incumbents have done a pretty amazing job in dramatically outperforming the president’s standing in the polls. The question now is whether the Obama drag will simply be too much for even the sturdiest of Democratic candidates to overcome.

One way to look at how serious of a burden the president is on Democrats – even those in traditionally blue and purple states – is to compare his job approval ratings today with those at this same point in 2012. What stands out the most – and what’s the most perilous for Democrats in 2014 – is how soured the so-called Obama coalition is on the Democratic president.

In the charts listed below, I’ve compiled data from the most recent NBC News/Marist polls from Iowa, Colorado, and North Carolina and compared it to data

More from the Cook Political Report