The Reds sold midfielder Brad Potts to Preston North End last week leaving supporters anxious that several other leading lights, including Ethan Pinnock and Kieffer Moore, remain at the club by the start of February.
Winkler, who believes the fee offered for Potts was a difficult one for a League One club to turn down, said: “I hope no more players go, but I cannot make any guarantees. But I can guarantee that everyone in the club wants to give us a strong squad, which can go for promotion.
“There is a thin line between doing a good job and good performance and all the clubs and recruitment guys from other teams looking at us.
“If you look at the list on Saturday at home games they come from everywhere in the country and Europe to watch our squad. We have a lot of interest.”
Despite the loss of Potts, Winkler retains confidence that the Reds have a strong enough squad to push for automatic promotion and in the club’s ability to improve it further.
He added: “We trust our squad and it is a strong squad. Our team is strong enough to stay in this position, but there are a lot of matches ahead of us.
“The most important thing is that we can (continue to) work with our squad because every player knows our style and philosophy and the surroundings. That is the most important.
“If there is anything from the outside we would also be happy. Right now, since I have been here, everyone at the club did a great job. We signed Kenny Dougall, Mike Bahre and Cauley Woodrow. All those players are in the starting XI and this is a 100 per cent outcome.”