Songo'o is currently on a month's loan from Portsmouth, but is not expected to remain at Palace beyond that.
A listless performance from the Frenchman in Saturday's draw with QPR resulted in him being substituted at half-time, and it is believed Warnock doesn't fancy giving him another chance.
Hughes joined Palace in the summer from League Two side Lincoln City, but has been told by Warnock that his first team opportunities will be limited.
Warnock told the Streatham Guardian: "I spoke to him last week and he is a really nice lad - but to me he is not a left-back or a left-winger, he's more of a left wing-back and I'm not going to play with three central defenders.
"He isn't on the transfer list, but if I can sort something out for him in the next week or so then I will."