The off-field uncertainty engulfing Newcastle United is expected to ease within the next fortnight, with at least one of the two American parties vying to buy the club now engaged in due diligence and Mike Ashley, the owner, formulating contingency plans in the event of a sale falling through that would include offering an extended contract to Joe Kinnear, the interim manager.

Although nothing is guaranteed, there is cautious hope that new owners will be in situ before January’s transfer window. Kinnear has stated that Newcastle’s match away to Chelsea on November 22 could be a “D-Day” for the club, after which he had been promised a “clear the air” meeting with Ashley, and that timescale still appears realistic. By then, it should be clear whether Newcastle’s purchase is viable.

The process of sifting through the company’s books by accountants and lawyers has begun, away from St James’ Park and at a six-figure cost. An estimated price for Newcastle, whom Ashley bought for about £140 million in the summer of 2007 before investing another £100 million to reduce debts, will already have been agreed, subject to the due diligence passing smoothly.

Those facts offer substance to the recent assurances by Keith Harris, chairman of Seymour Pierce, the investment bank charged with finding a buyer for the club, that the pair of United States-based businesses involved in the procedure are “two very serious contenders”. Philip Anschutz, the Los Angeles Galaxy owner, and Clark Hunt, who owns FC Dallas, have denied any interest in Newcastle.

Harris’s optimism, however, is tempered by the volatility of the global economic conditions, from which football is not immune. While there is quiet satisfaction that Newcastle’s prospective sale has reached an advanced stage, until a formal agreement is reached, there is nothing to prevent either company from walking away from a deal.

That eventuality may be as unpalatable to Ashley as it is to Newcastle supporters, who have established an independent representative body in the wake of the sportswear retailer’s management of the club, but it is feasible. In those circumstances, alternative arrangements will be necessary.

Kinnear and Nicky Butt, the experienced former England midfield player, have expressed concern that the haphazard, temporary nature of existence on Tyneside is affecting morale — the team remain in the Barclays Premier League relegation zone, albeit two points away from tenth position — and Ashley is keen to award the interim manager a contract until the end of the season if a sale is derailed.

Kinnear is working on a rolling monthly deal, the original terms of which were due to expire after the Chelsea game, and while the Irishman has helped to stabilise results, there has been little scope for long-term planning. Key players such as Michael Owen, Steve Harper and Butt fall out of contract next summer and negotiations on extensions have stalled. As things stand, Ashley will not encumber possible new owners with further financial ties.

Dennis Wise, the executive director (football), has also been seen publicly at St James’ Park this week, a rarity since Ashley, who is reported to have attended Tottenham Hotspur’s Uefa Cup tie against Dynamo Zagreb last week, announced his decision to leave. Wise was attending a schools community event at the stadium, a clear indication that the club are attempting to adopt a businesslike image. Kinnear has also said that he and Wise are compiling a list of transfer targets.

Kinnear will apologise to Martin Atkinson, the referee, whom he described as “Mickey Mouse” after Newcastle’s 2-1 defeat away to Fulham last weekend. The Irishman has been asked by the FA to explain his comments and could be handed a fine and touchline ban. “I am sorry if my post-match comments at Fulham caused any offence and I will ring Martin Atkinson to tell him,” Kinnear said.