It could be considered burning a bridge on the way you handle the situation. I would turn down the job, but do it in a way where I make myself look good doing i

It could be considered burning a bridge on the way you handle the situation. I would turn down the job, but do it in a way where I make myself look good doing it. I interview for the job, then let them know that you are very interested in the job, but due to prior work commitments you have to decline at the moment. You can tell them that you are in a serious project and that you are a crucial part of it. The project would be undermined if you abruptly leave. You can explain that you wouldn't want to leave in that type of situation and could explain there is currently not a set deadline. There would be other ways to handle it as well, and always keep in contact even if it's infrequent. You never know what circumstances may arise where you will need to find work right away.