The phrase “put something on ice” has both literal and figurative meanings. Just as you put some food in a cold place until needed, you can put a plan or a project on ice, meaning that you put it on hold for a period of time. “The project will be put on ice until money is available to implement it” In this case, a decision has been made to deal with the project at a much later date. Similarly, you can use the phrase “put something on the back burner” referring to something that has been temporarily suspended, especially because of its low priority. “Such issues must not to be put on the back burner.”