The only thing guaranteed is the Representative's Principle Nomination. If you have an LOA; that's great. However, you HAVE TO ME ON ONE OF THOSE NOMINATION LISTS. Each senator and your Rep are allowed to submit 10 names each. With an loa, you can be ANY OF THE 30 names. Without the LOA, you either have to be the principle or you will be competing in the pool. Presidential, VP, or any other nomination is simply that. Another nomination. You don't have to be on any of the MOC's list. My son had a presidential and received his appointment before EITHER senator or representative even started interviewing. So when they called about his interview, he simply thanked them for considering him and told them he already received his appointment. Therefor, please consider others for their nomination and not him.
Bottom line is a LETTER OF ASSURANCE is assuring you that you WILL get an appointment. ONLY however if you get a nomination and you pass any physical/medical requirements. They've already scored you and based on your score, and the average scores throughout history, then know that you are a "No Brainer". They will give you the appointment. However; they can't give you the appointment without you getting a nomination. CONTACT YOUR MOC. All 3 of them. Let them know you have an LOA. Ask them if they will be nominating you. Emphasize the point that the academy thinks enough of you to consider you part of the "No Brainer" club. Hopefully you MOC will see that and put you on their nomination list. Even if it's #10. Best of luck.... Mike.....