Wharton's comments came in his annual report to shareholders, released on Thursday, which revealed a loss of £1.95million for last season.
"Adjusting to life in League One proved to be more difficult than we anticipated. The poor performances on the pitch, particularly at home, led to a decline in attendances and gate income was well below budget," he said.
"The drop in total income which I predicted at £4million in fact became £4.5m, and we were only able to reduce costs by £2m. It is stating the obvious when I say further drastic reduction in our operating costs are essential to ensure our ultimate survival."
Wharton re-iterated his commitment to step aside from the club in the summer, when he will resign as chairman and as a director.
He has put in a £2m loan to cover an expected operating loss for this season, but the club's future beyond the summer remains unclear as further budget cuts seems impossible to avoid.
"I reported last year that I was seeking a successor. Sadly I am finding it extremely difficult to find anyone remotely interested," said Wharton.
He offered his backing to the Iron Trust, the club's supporters trust who launched in the summer with the aim of putting a fans voice in the boardroom.
"I would urge all our fans to support the Trust in any way they can," he added.
"Whilst I think it would be an impossible task for the Trust to have total control of the company, I do think it is important our fans can have as close a relationship as possible with the board of directors."
The Iron Trust, whose interim board are due to meet with the SUFC board of directors next week, had 191 members as of Wednesday evening.
Membership of the Iron Trust until the end of this season costs £10 for adults, £3 for U16s or £20 for families (2x adults + unlimited U16s). Join by stopping by the Trust Corner before home games or by going to www.theirontrust.com. More details of the club's financial performance will be published on Iron-Bru.net over the coming days