Chris Coleman says Sunderland are working tirelessly to find replacements for James Vaughan and Lewis Grabban.
It looks increasingly like Josh Maja will again be the club's only recognised striker against Hull City on Saturday, with the Tigers just three points ahead in the Championship table.
Sunderland retain some hope that a signing can be made in time but it looks unlikely to be either Jon Walters or Ben Woodburn.
Walters tweeted on Wednesday night to suggest he has suffered another injury after long-term knee problems, while Liverpool are increasingly reluctant to loan out Woodburn following Philippe Coutinho's departure.
Maja is set to lead the line for only the fourth time in senior football and Coleman says the club are fully aware of the need to secure reinforcements.
He said: "We’ve got to look at that [up front]. We’ve got two experienced players to replace and to help Josh. I don’t think we can do anymore than we’re doing to make something happen, we’re fully aware of the seriousness of it."
The Black Cats have an interest in Manchester City youngster Lukas Nmecha, while Derby County target man Chris Martin has also been linked with a short-term switch. Gary Rowett has confirmed that the Scottish international could leave the club this month.
Coleman has so far made one signing this month and he again praised the attitude and hunger of young defender Jake Clarke-Salter.
He admitted, however, that like any signing he makes this month, the youngster still needs to make progress on his match fitness. Coleman hopes to add some experience to his squad to ease the burden on a cohort of youngsters that have broken through in recent weeks.
Coleman said: "Most of the players you bring in the January window won’t be match fit.
"You can play U23’s but it isn’t the same as senior football. Jake hasn’t played for seven weeks, and I liked a lot of what I saw.
"Yeah we were disappointed with one or two of the goals [against Cardiff], we’ve talked about that.
"But he’s going to get better and he’ll get great experience, the club and the player will compliment each other. He wants to learn and you want that, you can always get better no matter how old you are.
"There’s plenty to work with [young players]. I know results haven’t been good but we have to look at what individuals are taking from it too, and these experiences will mould the youngsters. We need to add some experience and we’re trying. The players we have now are probably having more exposure than we’d like, nevertheless, they’ll get better for it."