Keith's 16 May update: According to NASA PAO there is "no Orion program interest in buying another Delta". That said there have been meetings at NASA where this was openly discussed - since I have spoken to people who have been in those meetings. What constitutes "program interest" means different things to different people. If there is no interest in the topic then why do they talk about it at meetings?

Keith's 15 May note: Sources within NASA report that there is interest in buying another Delta IV Heavy for an Orion mission. NASA launched the first Orion mission - EFT-1 on a Delta IV Heavy in 2014. Speculation about the interest in another Orion flight on a Delta IV Heavy often surfaces with an expression of doubt with regard to the future viability of SLS and whether it will be used to loft human crews. Some have suggested that Lockheed Martin may propose an Orion variant for a future commercial crew procurement opportunity. Congress has also expressed renewed interest in Orion visits to ISS and put language into the NASA Transition Authorization Act of 2017 addressed "the ability of Orion to meet the needs and the minimum capability requirements described in section 303(b)(3) of the National Aeronautics and Space Administration Authorization Act of 2010." NASA was supposed to deliver a report to Congress within 60 days of the bill becoming law - which means that the report is past due. Oh yes: Delta IV Heavy is not human rated - yet. Stay tuned.