United are just one availability blow away from having to push the loan button before the Football League window closes later this month.
The Pools boss has the flexibility within his squad to add to his squad before the deadline for emergency loan passes on Thursday, March 27.
But he is reluctant to make the wrong move at this stage in case another player is ruled out for a significant amount of time in the next few weeks.
The departure of Jack Baldwin to Peterborough on January transfer deadline day has left Hartlepool short of defensive cover at the heart of the defence should anything happen to Sam Collins or Christian Burgess.
But Cooper is also reluctant to bring in a new centre-back at this stage, with the pair of them playing well and he knows it could be further forward where he needs a new addition by the end of March.
“There's two things, I have to be careful I don't batter the life out of Sam,” said Cooper. “But we are one twist, tackle or suspension away from being very short in numbers.
“I am ready to react if something does happen. Rather than bring somebody in just to sit, I think the job needs to be to react if something does happen. That's the best way to do it.”
Hartlepool have lost Matty Dolan in the central midfield area and Luke Williams further forwards – both returned to Middlesbrough after loans - in recent months which has restricted the options behind the strikers.
While Cooper, whose side are looking for a return to winning ways at home to Bristol Rovers on Saturday following Tuesday's goalless draw at Accrington Stanley, is monitoring the market, he is also looking for a new No 2.
Craig Hignett's sudden departure to Middlesbrough ten days ago has effectively left Cooper without a right-hand man and he is considering his options. He hinted it could be next week when things start to roll. Cooper said: “There is still a situation between Hartlepool and Middlesbrough to be resolved between the two clubs. There is a 14-day period for that to run until that has elapsed. When that has I have put some suggestions forward to the chairman (Ken Hodcroft) and we will see what happens.”
Former Middlesbrough coach Mark Proctor, ex-Sunderland boss Malcolm Crosby and Mark Venus, the former Boro No 2, are among those to have been mooted.