The former Coventry City keeper, who performed heroics for Northern Ireland on Saturday night against Italy, has a year left on his contract.
Tuffey has been watched by Scottish Champions Rangers and has had reported interest from Championship clubs.
Said McCall who has signed a three year contract at Firhill to The Glaswegian.co.uk: "I think for the likes of Harkins, Tuffey and Twaddle this may have a bearing on them.
"They are all under contact for another year but we would like to try and get them signed up for an extra year. Then, if we don't manage to compete at the top of the league this year, they can go away.
"Mind you, if the clubs who are interested in Jonny want to buy him and loan him back to us for a year we have no qualms with that. "But I think they are all keen to stay for at least another year."