I do not think it would be an Echinocereus.
@misslilthings, I am surprised you would say that Echinocerei are common house cacti as I rarely see these plants for sale in the Big Box stores, at more specialized cactus nurseries and botanical garden plant sales for sure, but while these are great landscape plants under the right conditions, I think many people would have a hard time keeping these alive in-house, maybe in a green house.
Maybe you meant Echinopsis?
My guess would be that it is Echinopsis calochlora or a hybrid there-of, but as Daisy says the bloom will say it all, and some kind of Lobelia, Notocactus, or Chamaecereus could also be a possibility.
