The United States Postal Service will try same-day delivery service this holiday season in...

The United States Postal Service will try same-day delivery service this holiday season in select markets. Under an ambitious plan, the USPS wants to work out agreements with national retailers to service their same-day delivery needs. Should FedEx (FDX -0.6%) and UPS (UPS +0.2%) be worried? Though the government's scale is big enough to pose a threat, doubters see mounting budgetary issues preventing a wide rollout of same-day delivery.