Reports over the past few days have speculated that Ramsden - who was poised to receive a£9 million pay-off for relinquishing a management role in the business he founded in 1977 - will face a vote against him at the annual shareholders' conference on November 28.
The Times and The Daily Telegraph reported that Ramsden's role in the aborted merger was being probed by a committee of non-executive directors who would present their findings at a meeting next Wednesday.
'The shareholder members are well aware of my achievements and what they have earned out of being Nisa-Today's members. I was responsible for building a buying group that ultimately has become the second largest independent buying group in Europe,' Ramsden told The Times.
A Nisa-Today's source told Retail Week today: 'We were all very shocked when we heard about the stories.'
The source added that senior management had been locked in meetings today discussing how to respond to the issues raised.
Ramsden called time on the long-running merger saga on Monday after his Icelandic backer, Kaupthing, demanded that extra strings be attached to the deal.
The merger was proposed in May this year in order for Costcutter, which has nearly 2,200 convenience stores, and Nisa-Today's, which has 700 members, to survive competition from large retailers such as Tesco and Sainsbury's moving into the convenience market.
Nobody at Nisa-Today's is available for comment.