The Democratic nominee is easy: O'Malley of Maryland. He meets the democrat profile: Governor out of the blue, No Federal experience, nice smile, makes good speeches. This is enough a la Carter, Clinton, etc. Dems are suckers for such. I suspect Hillary will decide not to run.
BUT the election may turn of on a factor no one seems to be willing to discuss. O'Malley and many of the Republican candidates are Catholic, including, Jeb Bush, Rubio, Paul Ryan, Christie, perhaps others I forget.
This is more important than it would be in other years. Immigration should be a critical issue and may still be. BUT the Catholic Bishops have taken as strong position in favor of massive immigration of Latin Americans into the US and massive welfare and social programs for them. And, surprise, surprise, all the Catholic candidates favor massive immigration etc.
No politician and, indeed, no journalists seem willing to discuss this issue. Clearly, Catholics have enough votes to swing most elections. so it is a dangerous issue. Even the evangelical Protestants avoid or do not yet see the issue.
AND Protestants no longer can control the election, and many would agree with the Bishops agenda.
This makes the Republican nominee difficult to predict. My guess is that this issue will remain unspoken, but the immigration issue will give the GOP nomination to Walker. Since this is a Republican year, he will win. But I do not feel strongly at this time. I would not bet much money against O'Malley. I would bet the farm against Hillary.