It depends on how far along you are in the process to see if you want to change. Your contract should have a mortgage contingency date on it. If you are going USDA you are going to need a month for approval and if you are coming upon your contingency date soon, then I would wait on jumping ship and finding another lending. If you think the loan officer is not capable, you can always talk to a supervisor and have another loan officer assist you with your loan.
I hope it works out for you.
Good luck with your new home!
CG Real Estate
I'll defer to Jill on answering program specific questions since she keeps up on each program's details as that's her job as a mortgage originator.