The Dems are in no hurry. As long as O'Connor sits on cases, any 5-4 rulings that she votes on would have to be reconsidered if she is not on the Court when the decisions are announced.
O'Connor might want them to hurry up, though.
The pressure will come from the people, and the fact that if the dems reject a nominee or two, they will look like the intolerant jerks they are, even in the MSM.