Depending on your skill and demand, you could simply nudge them by asking if they are considering an offer because youll need to make a decision soon, as you do

Depending on your skill and demand, you could simply nudge them by asking if they are considering an offer because youll need to make a decision soon, as you don't want other companies to wait simply because they responded quickly. This communicates you have options, and that they are going slower than you'd like. Clearly this only works in certain situations and can be dangerous if executed poorly.