Last-minute surges and last-minute deciders are of course important in our primary. I have little to say to those voters, because I don't understand them and I don't know what motivates them. But the field is already narrowed for them by the time they get to that last two weeks by the accumulated support of slower - not necessarily wiser - choosers among the larger field. I think I understand those a bit better.
If you are one, you are just about to enter dangerous territory. Labor Day and the restarting of the school year is one of the last check points before serious confirmation bias sets in. If you don't get this under control, you are going to quickly become one of those people you regret, right around oh, Feb 10 or so. You will double down repeatedly no matter what the news is. You will have chosen your guy/gal, and even if they strangle a puppy on live TV you will tell co-workers the next morning that the puppy deserved it, and besides, everyone knows it's the other party that strangles more puppies.
If you don't think you have confirmation bias, then your case of confirmation bias is probably particularly bad, yea, even incurable. (See also, Dunning-Kruger Effect.) Everyone, everyone has it, and it is only avoided by specific effort.
Here's something you can do about it, just to smack yourself back into your senses a bit: pretend, to yourself and with courage even to others, that you are a supporter of one of the candidates who is doing poorly in the polls right now. You don't even have to switch parties (that's a pretty hard exercise anyway), as there are intelligent, decent people unable to get any traction in both places. Pick one you sorta liked anyway, or look for the positive in someone you don't know much about. You can even tell pollsters you are supporting them - I think there is a general exemption on the Commandment about bearing false witness when it comes to polls anyway. Theologians are standing by to help.
Leading in the polls is a matter of money or charisma at this point. (The ability to inspire anger is also a form of charisma, remember.) You will note, when you stop hyperventilating, that neither of those things is that important a quality for a president. They each might be net negatives. So pick someone going nowhere and believe in them. It will do you good. Really, it will do us all good.
You can get some of your best self back this way, before the quadrennial idiocy descends upon us.
BTW, I can't recall who I voted for in half the primaries since 1976. I recall caring deeply at the time.