We'd say this overstates the case - in a good many states, there are lots of self-described Democrats who vote mostly Republican. And it seems to misstate the case in the South and in parts of Appalachia.
Still, you now have the pollster Gallup concluding that just four states (Idaho, plus Utah, Wyoming and Alaska) are "solid Republican" states, and just one more (Nebraska, which gave up one electoral vote last year to Barack Obama) as "leans" Republican. (The actual ranking for Republican-ness is, Utah, Wyoming, Idaho, Alaska, Nebraska, Kansas and Alabama.)
Washington and Oregon, as you might thereby expect, are listed as "solid Democratic."