Cardiff City boss Erol Bulut said he could leave the Championship club and "doesn't know" if he wants to stay on unless the club make signings.
A 3-1 defeat at Plymouth has seen Cardiff slip to 14th in the table, six points off the play-off places.
Bulut has called for signings for weeks and has now said he is considering his future with the club.
"I am not happy with many things," he said. I have to decide about myself and the future with the club."
"I will make a decision about that.
"I have to maybe make a decision for myself on how my future will go with the club, because I came here to change some things in a positive way.
"I don't know (if will continue until the end of the season), I don't know."
Cardiff named former Fenerbahce boss Bulut as their manager in June but he is warning that signings this January are integral as to whether he will remain with the club.
"From my side I can tell you that some things have to change. If not, [it is] not possible to continue like that," he told BBC Radio Wales Sport.
When asked, 'what has to change?' he replied: "Everything."
Bulut says he will have discussions with the Cardiff board and seek assurances signings are coming, but says the the Bluebirds will struggle without reinforcements.
"I will speak to the board clearly about everything that has to change," he said.
"We now have two weeks until the next game and I think from now everything can change.
"I don't know about signings. I spoke about that. We are too late with many things.
"We tried to change many things, but alone you cannot do nothing.
"So we have to make many changes and if this is not changing, we will have big problems until the end of the season.
"Everyone knows (we need players), I know it, the board knows it, the fans know it, all of us, we know it.
"We have worked hard to come to this position… until now we've only been three points off the play-offs, but now we cannot speak about the play-offs, now we must speak about different things.
"If we don't get signings? We will have to fight with what we have, but we will have hard weeks and months in front of us."
Cardiff's players were booed by their travelling fans at Home Park and Bulut said he understood the frustration.
"I can understand the frustration of the fans, I am frustrated also," he added.
"But I have some things in my hands to change something and some things I don't have in my hands to change it."