This race won't be settled by a dearth of resources on either side. If the district had a greater take of the KC area (and not its more conservative suburbs), Barnes might be leading right now. I tend to be pessimistic about Democrats' chances of reclaiming rural seats like this that they lost in the early 2000s.
Like most in most other close House races, up-ballot conditions could determine the outcome.
Jay Nixon is likely to win this district in the governor's race, but McCain will likely win it for President unless Obama carries the state.