But with the Gills just above the League Two drop zone Hessenthaler told BBC Radio Kent: "We don't regret saying what we said about getting promotion.
"That's what we thought we'd do. At the moment it's getting tough to do that."
Hessenthaler returned to Priestfield for his second spell in charge following the Gills' relegation in May.
At the time of the appointment Scally said: "He [Hessenthaler] buys into the package that anything less than promotion is failure.
If we're not in the position we should be come January then the chairman will obviously make decisions
Andy Hessenthaler
"We'll be aiming for top three and we want everyone to buy into that concept. Anything less than promotion back to League One will be disappointing."
But six months on, Hessenthaler insisted their difficulties were largely down to his depleted squad.
He said: "I don't think the chairman realised we'd have as many problems as we've had this year with injuries.
"At the start of the season we thought we were going to get everyone back and unfortunately we've had a problem with that and I think he realises that.
"But nine points is a small gap . Liverpool were struggling - they couldn't get a win and all of a sudden they win three and draw one and things are rosier for them.
"You need to just get a few wins behind you and the confidence will come back.
"But if we're not in the position we should be come January then the chairman will obviously make decisions but he's right behind me and for me that's great."
Source: BBC Sport
Source: BBC Sport