I am currently in a co-op position at company A during my current school year. This co-op is scheduled to end in the Spring, and I have received an offer from company A for full-time permanent employment thereafter. This offer is currently pending.
I also applied for a full-time permanent position at company B. I received an offer from company B and have accepted it.
I now need to decline the offer from company A. However, I would still like to finish out my co-op position. How can I speak such that it's clear I'm still enthusiastic about my current project while also making it clear that I have already made a final decision in regards to moving to company B?