IMO, the candidate that's going to win is the one that uses the favored Repub tactic of selling fear the most effectively. In other words, those voters of the parties that feel the most threatened will bring out the most votes.
The Repubs will be/are bringing out the usual single issue boogymen like Obamacare, illegal immigrants over-running the country, same sex marriage, abortion and the vaunted use of their well oiled rumor mill to scare their base into coming out to vote.
The Dems, well, it seems the Dems are outgunned as usual in their purveying of fear as a method of motivating their voters to care enough to vote. They can sell to their base how the Repubs in D.C. want to take their Social Security and Medicare away, and how the Repubs want to take their ability to vote away via their Voter ID Laws, along with the Repub's habit of taking care of the rich at the expense of the middle class and the poor.....all useful and effective motivators.
But the DNC simply lack the nerve and verve to effectively pound away at these issues 24/7 like the Repubs do theirs. Instead, it seems the Dem higher ups default to ignoring and pooh-pooh'ing both the real threats against their voters and the mud and unsubstantiated crap the Repubs are constantly flinging at them, espeically on the public forum.
The RNC simply does more with less (real issue-wise) by repeatedly shouting a whole lot louder on narrowly defined issues (contrived-wise) and spending cash and resources a whole lot more liberally.
It's a formula that clearly works well for them, of which it seems the DNC should be emulating in their own fashion.