The Cook Political Report Partisan Voter Index is an attempt to categorize how much more red or blue a state is compared to a national average. It works by taking the average national two party vote share of the past two elections and calling that the zero index value. States with vote shares for the Democrats that are above that index value are considered to have a D+x PVI. States that vote more Republican than the index value are considered to have an R+x PVI. It is very closely related to the hypothetical uniform swing.
It is a decent indicator of partisan lean of a state although it lags on fast changes (The eastern mountain states probably have an actual PVI above the reported PVI).
I want to point out some of the states whose Senators voted for PPACA and what their 2010 PVI was as a public service announcement:
North Dakota R+10 *
North Dakota R+10
South Dakota R+9,
West Virginia R+8
West Virginia R+8 *
Only two of those seats are still held by Democrats. None of those seats are on the top tier of the Democratic target list for 2016.
These ten seats were a minimal majority blocking coalition. Another 8 Democrats were sitting in Republican leaning seats and plus the asshat Lieberman as a massive opportunity cost in Connecticut. That is 19 Democrats in the Senate including any plausible majority combination where fulfilling major liberal policy goals was either personally distasteful (at least 1) or politically challenging giving their home turf. The actual policy space was severely constrained.