If it was me I would press a little bit and float the idea that I have other prospects in the works. Say something like "I would really like to work for your company, it is my first choice, but I don't intend to stay available on the market for long". Showing confidence in my abilities has always worked in the past. Make sure to time it right, maybe it's best to do that kind of thing early Monday morning rather than later in the week and if you have any feel for the flow of their business try to do it during a positive time.