Control of the white house is need to pack a court. Who currently has it?
In the long run all of this has to get past the supreme court. Some of the reason it has is that justices appointed by republican presidents have tended to liberalize a bit with time, and not rule as they were expected to. Which is why the conservatives are being so careful to try to find justices that will stay that way, and rule out anyone who betrays the slightest hint of possibly growing up some day ;-)