With Tony Mowbray under pressure to raise funds and reduce Boro's overblown wage bill when the transfer window reopens in less than two weeks, O'Neil is one of the senior figures expected to leave the Riverside.
Premier League duo Stoke and Everton have scouted the former Portsmouth midfielder on a number of occasions, while Bolton are also understood to be considering a loan move.
O'Neil's future has been a regular source of conjecture in previous transfer windows.
Having seen his name linked to a range of clubs since moving to Middlesbrough in August 2007, the 27-year-old insists the latest bout of speculation will be like water off a duck's back.
It wouldn't be January if I wasn't being linked with a move, said O'Neil. I'm sure the press will generate something about me and I'll be asked loads of different questions about the same old clubs.
I still keep hearing that I'm unsettled in the North- East, but I've supposedly been unsettled in the North- East for three-and-a-half years now, so I must be doing something right.
I'm expecting some more rumours, but they definitely won't affect me. I'll do what I always do and ignore them, and I'll concentrate on trying to get the points we badly need. I won't be thinking about anything apart from improving Middlesbrough's position in the table.
Boro's position did not worsen over the weekend, with Preston and Scunthorpe losing games to the weather and Crystal Palace losing 3-0 at Nottingham Forest.
However, the Teessiders will still enter the festive period in 21st position, with only goal difference keeping them out of the bottom three.
Friday night's 2-1 defeat at Doncaster was a particularly bitter blow, with Boro dominating for the majority of the second half, only for a stoppage-time error from goalkeeper Jason Steele to hand Rovers all three points.
O'Neil admits the atmosphere in the Keepmoat Stadium dressing room was especially downbeat after the final whistle.
But with recent performances having represented a marked improvement from the form of two or three months ago, optimism remains ahead of a Boxing Day home game with Nottingham Forest and a trip to Preston two days later.
Friday's defeat was the hardest one to take this season, and that's saying something, said the midfielder. To be that dominant and so much in control, but then to lose in the last minute was hard to take.
When you're in a relegation battle you can sometimes feel under pressure during the game and think that bad things are going to happen.
On Friday, we felt really comfortable because we were so in control. So to come away with nothing again was massively disappointing.
But the positive is that the last three performances have been good enough to win all three games.
Coventry, Cardiff and Doncaster we might only have won one, but I think the performances have definitely picked up since the gaffer has come in and that is a plus.
In particular, O'Neil feels Boro are finally starting to create the opportunities required to win a game. On Friday, those opportunities went begging, with Kris Boyd's 89th-minute miss proving particularly costly.
On another day, however, a higher conversion rate would have resulted in a much-needed win.
We still have to brush up in both penalty areas, but I don't think it's a lack of creating chances now, said O'Neil. A few months ago, we weren't creating the chances. Now, we're just not taking them, but that's easier to put right.
We look like we're capable of winning games, and I can't see Jason making a mistake like Friday night's again. We need to improve in both penalty areas, but the attitude of the lads over the last three games has been really good.
It will have to be every bit as good on Sunday, as Boro take on a Forest side who have lost just one of their last six matches, and while O'Neil is all but certain to start that game, it remains to be seen whether he will be fit enough to also face Preston two days later.
I generally struggle with my groin and hip a couple of days after a game, so we'll have to see how things go,
he said. But I'm hopeful I can play in all the matches.
The Preston game on the 28th will be a bit of a test, but hopefully with another week's full training between now and the weekend I'll be okay.
I've had three games on the trot now without any niggles. When the gaffer came in, I told him I could really do with a week with the physios because things weren't quite right. He let me do that, which was good of him, and I think my form has improved for that.
Source: Northern Echo
Source: Northern Echo