I think that would still count as just conspiracy to commit murder. Not a good thing to do by any means, but not everyone follows through on their plans, so it's a lesser crime.

An attempt likely requires an actual failed attack against the target. It's much more severe.

EDIT: On second thought, I can see how you could consider hiring a hitman as an attempted attack, since once you have agreed upon the hit, the "weapon" has in effect been "fired".