Would you still apply even if the boss wants someone else?

I'd still apply, although I wouldn't get my heart set on it.

The "feeling" may or may not be correct. The department head may or may not have the weight to force the issue.

Apply. Give it your best during the interview as if you were the most viable candidate. Make them choose between you and someone else. Even if they have someone in mind, you will be the obvious best candidate the next time.

Apply anyway. If you don't, it's a 100% chance that you won't get the job. If you do, it's a less than 100% chance of them passing on you. I'd rather take that chance.

I agree with the people who say that you should apply. Even if you don't get THIS job, there may be someone in the group doing the interviewing who might be interested in you for another position.

Well, sure! Apply! What have you got to lose?!

Apply! The other guy could get run over by a bus...

You have nothing to lose and everything to gain. You could make a really good impression for another, future position. Of if this guy doesn't work out, you could be next in line.

Nothing ventured, nothing gained. Trite but true.

I agree with the others - apply. 1) If there is more than one person making this decision and what you believe is true, then you do have a true shot; 2) you don't know for sure if this is the department head's true feeling/thoughts as it is simply rumor; 3) it shows you are interested and in the interview you can point out your strengths - even if you do not get the position, it will put you in a better running for future promotions.

If after the selection is made and it isn't you, schedule a follow up - if they don't already do this and discuss what you should work on in order to be promoted in the future and then work on it and keep documents of your progress.

And yes, I've been in that position several times - once I did get the promotion - sometimes true hard facts when pointed out in interview are too hard for department heads to overlook.

I've been in the other position as well. I was starting a new group and some one applied for the position I didn't expect. After meeting and interviewing him - he ended up getting the position.