We are moving quickly into second interviews. What is your availability like over the next few days?

Remain professional and objective. Considering how competitive this opportunity is, being completely available and ready for the next stage when it is presented reflects that you have planned well for this opportunity. A willingness to be flexible, while conveying hopeful enthusiasm is the tone you'll want to strike.

"Thank you for presenting me with the opportunity to sit and talk with you. This has been an honor. Should I receive the good news I have the opportunity to move into the next stage of the interview process, I will shift any other priority I have and make myself available. So, to answer your question, my availability is wide open."