State-Level Presidential Approval

Gallup reports:

A majority of residents in 13 states and the District of Columbia approved of the job Barack Obama did as president during the first six months of 2012. His highest ratings by state were in Hawaii (63%) and Rhode Island (58%), in addition to the 83% approval from District of Columbia residents. In 16 states, his approval rating averaged below 40%, with residents of Utah, Wyoming, and Alaska least approving.
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The list of states in which Obama had majority approval during the first half of the year includes three of the largest states -- California, New York, and Illinois. This helps boost the combined Electoral College vote of states with majority approval of Obama to a total of 185. All of these states have voted reliably for Democratic presidential candidates in recent elections.

Most of the 16 states in which Obama's approval rating is below 40% tend to be smaller in population and thus have fewer electoral votes. The largest of these are Tennessee and Indiana with 11 electoral votes each. The 16 states with approval ratings lower than 40% total 93 electoral votes, and typically have supported Republican presidential candidates in recent elections.

That leaves 21 states in which Obama's approval rating is between 40% and 50%, including some of the largest "swing states" such as Florida (46%), Pennsylvania (46%), and Ohio (44%).