Maine is a small state, and small states like to keep their senators for ages to get the goodies senior congresspeople can bring. Perhaps this tendency will change as the national mood and budget hawkery kills off "earmark culture" - I think the sun has set on the Ted Stevens/Dan Inouye/Rob Byrd types for good.
The best Bellows can do is hope to outperform Allen. Not entirely beyond the realms of possibility - 2014 reflects a vastly more polarised electorate than 2008, with more "one party" voters - but still unlikely given the political weather and the weaker (
sorry Bellows ) candidate.