The three previous posts include Republicans and Democrats who are at different levels of candidacy.
Strangely absent as having announced officially her intentions, leading us to presume she's insecure about her leadership abilities, is Hillary Clinton. Apparently playing the game of being fashionably late to the party, she will come in with much fan fair and trumpets, the newspapers will clamor to say it first, and she will announce.
If he does not run, her supporters will feel shammed, like a teenage boy who leans in for a kiss at the end of prom night and is rejected with a tease. If she does run, she will show her hand as being able (or wishing she were able) to push around the media.
Also, and I say that firmly, also, are third party candidates listed in their own post. It is a tough place, since not one has a chance to win. This is an election in which the Democrats will be only split in just a few directions. The Green Party (etc.) will draw from the Democrats, as they always do, and no card carrying Democrat, and certainly no anti-Republican will risk the election on a third party vote.
Whatever the pros and cons are of a two-party system, this will not be their year of influence.
I'm not against third parties. I support them. I hope they run, and hope they do influence the election. I wish that one would rise up as an alternative.