The Black Cats have struggled for results this season, but four wins from their last eight games - including a 1-0 home victory over champions Manchester City - have taken them to 11th position in the table, nine points above the relegation zone.
Steven Fletcher has been in fine form for the club since his summer arrival from Wolves, but O'Neill is looking for further options up front in order to drive the club onwards.
"I don’t want to talk about individuals at other clubs - that's not my remit," O'Neill told The Shields Gazette. "But what I would say is that at this stage we do have several irons in the fire when it comes to reinforcing ourselves up front. We are looking at a variety of players, not just the one."
O'Neill admits the festive period has been a hectic one for the club, but he is looking forward to a rare break next weekend in order to give his squad a rest and concentrate on bringing in new signings.
"It has been a busy time for us with a lot of games, as well as the [transfer] window, but it will settle down a bit next week with no game to play and maybe then we can force one or two things along," O'Neill said.
"Players are leaving and need to be replaced in the squad. By the same token, we don't want to leave ourselves short at the end of the transfer window. We recalled [Ahmed] Elmohamady from Hull City this week for that reason - because we need more bodies. And we have to think twice about letting anyone go at the moment if we can't get replacements in.”