The Senegal international struck twice before the break to put 10-man Wigan, who had Maynor Figueroa dismissed, on the back foot and pave the way for a 3-0 win, with Gael Bigirimana scoring his first goal for the club, which ended a sequence of four successive Premier League defeats.
Manager Alan Pardew admitted Ba's clause, which will become active in January, remains in place, but is hopeful of hanging on to a man whose goals have proved vital.
Pardew said: "The truth of it is that Demba has got a clause in his contract and it is still hanging over us. We have tried to negotiate away and we have not managed to do that as yet."
The Magpies boss added: "But the one thing I will say on a positive note is that he has never, if I am honest, looked me in the eye and looked like he wanted to do anything else but stay here, and I hope he does."
Pardew was a relieved man as he savoured a win which could not have come at a better time.
He said: "It was a massive victory for us, and I am very proud of my staff and my players because we have had to stand tall. Four defeats in this city isn't easy for any team, I don't think. There was a lot of pressure on us."
Opposite number Roberto Martinez was bemused by the sending-off of Figueroa, a decision which he believed proved key. The Spaniard, who revealed the club will consider an appeal, said: "You need to understand, Maynor is as honest as you are going to get. He is one of the most honest footballers I have ever worked with.
"When he makes a rash challenge, or if he makes a challenge he feels is clearly breaking the law, he will accept responsibility. He was destroyed. He was very, very upset at half-time. All he was saying was, 'I challenged, I went shoulder-to-shoulder and the ball was there to be won'.
"If you look at the replay, that's exactly what it was, so I do feel for my player. He didn't do much wrong. It's a decision that really changes the dynamics of the game, but then to concede from a penalty is clearly a double punishment."
Pardew, meanwhile, saw Ba, Santon and Cheick Tiote all limp off, but is hopeful all three will be fit for next Monday's trip to Fulham.