Oregon is one of the last states that would have a problem with Obama's shift on marriage equality.
http://www.uselectionatlas.org/RESULTS/state.php?fips=41&year=2004&f=0&off=60&elect=0
Granted, that was back in 2004, and it's even possible that a narrow majority now supports it in OR. But it's also a safe bet to say that gay marriage is less popular than the Democratic Party in Oregon (ditto for every other state, probably), and therefore Obama's shift is going to be a net negative for him there.
2004 is a lifetime ago in politics, there have been a lot of big shifts since then. Bush didn't even win the state with that result on marriage equality and it likely wasn't the reason he even got close.