If you told me in 2004 that Democrats would spend 2012 cheerfully defending 8% unemployment, $4.00/gallon gasoline and 16-25% underemployment, I would have called you crazy and told you that significant portions of the Democratic base would support Ralph Nader or somebody like him in 2012.
The Democrats could run a proto-fascist and as long as the Republican is more conservative, they'll always justify voting for the Democrat. After numerous things Obama is guilty of and the fact that so many still support him, I'm convinced that the answer to my question "Where do you draw the line?" to Democrats is "nowhere."
