Why is Gang of Six plan "practical" but Cut, Cap and Balance will never pass?

Have you noticed the unstated assumption shaping much of the reporting and commentary on the Gang of Six (Go6) plan and the Cut, Cap and Balance Act of 2011 (CCB) just passed by the House?

One of the Gang of Six – Sen. Dick Durbin, D-IL, conceded yesterday that the Go6 plan consists only of “concepts” that he and his five cohorts on the group agreed to after six months of behind-closed-doors dickering. The Go6 plan hasn’t been put into legislative language, therefore, Durbin admitted, the proposal “is not ready for prime time.”