I prefer FiveThirtyEight to Real Clear Politics. As they point out frequently, national polls mean little or nothing in the primary race because primary elections don't work the way polls do. The rules are also malleable right up to the moment before the actual selection takes place at the convention.
FiveThirtyEight places a great deal of weight on what it calls the Endorsement Primary. This is a points system where each endorsement of a candidate by a member of the House of Representatives is worth one point, each Senator's endorsement is worth five points, and each governor's is worth 10 points. By this scale, there are theoretically up to 1435 points to award, though members of one party are unlikely to endorse someone from another party. In any case, Clinton leads the Endorsement Primary for Democrats by 447 to Sanders's mere 2 points (and O'Malley has one point). Republicans are a much more mixed bag with Bush at 41, Rubio at 29, Christie at 25, and Huckabee at 24. Everyone else is at 15 or fewer points (Trump and Carson have zero), and only 168 points worth of endorsements have even been made among candidates still in the race, so there's still a lot of wait-and-see going on.
I expect the party will push for some of the others to drop out to make the Iowa slate a little cleaner, but Iowa and New Hampshire are worthless as predictors of the nation, doing little better than chance at predicting the actual nominee. They act as filters: if you can't make a halfway decent showing there, you're probably not going to do it elsewhere. But ultimately, the party has a great deal of control by pushing superdelegates to vote in a certain way, and even a seemingly close match-up going into the convention could turn out to be a nearly runaway victory for whomever the Establishment prefers.