‘How Much Time Can I Ask for to Consider a Job Offer?’

Dear Boss,

I’ve been conducting a low-key job search for months without much movement and now, suddenly, have what seems like serious interest from two different companies. I’m near the end of the interviewing process with both of them, but, from what I can tell, one of them is moving much more quickly than the other. I’m open to both, but I’m more interested in Company A. Of course, Company A is the one that’s moving more slowly.