You have probably noticed that Amazon has pulled next-day and same-day shipping options when checking out in recent weeks, presumably because the company's warehouses are drowning in holiday orders.
The good news is, there is a way around it. Your experience may vary, but it just worked for this week.
After you place your order, immediately click on "Your Orders".
(Do it quickly, you generally only have a few minutes at most).
Find the order you just placed, then click the "Change Shipping Speed" button.