Dear Mr. Potter:
I am most excited to receive your letter of December 12, 2004 informing me of the upcoming interview on December 17 in connection with my application for the position of Project Coordinator.
However, I am writing to inquire if there is any possibility of rescheduling the date for the interview. I am very much interested in this position, yet unfortunately, I have a professional certification exam scheduled for the same day. This exam is held only twice a year, and I would have to wait until next June if I miss this one.
I apologize for any inconvenience that the rescheduling might cause you, but I ask for your understanding and assistance in making another appointment for our meeting. Thank you very much.