Moving images from one collection to another, not copying

I'd like to use collections for the following scenario:

I have picked a number of images that I want to publish on different web platforms. As I won't throw them all there at once, I need some kind of backlog to keep them selected. A normal collection seems the right thing to do here. When I have published an image, I want to note that so I won't publish the same image again anytime soon. Also, I don't want to simply remove the image from the collection so that I still know what I have published in the past so I can reuse the same collection for something else. So I'd use a second collection named "published". Then I need to move each published image from one to the other collection since both sets are logically mutually exclusive.

I could use two collections in another way, like "yet to be published" and "all selected" where the second never changes and images are simply removed from the first one. The second collection would then be a superset of the first. But when I refine my selection or add new images, I'll have to update two collections, not one. That's more work and error-prone.

So for now, I'm looking for a simple method to move an image from the currently selected collection into another collection. I can copy images, but then still need to press the Delete key to remove them from the source.

I haven't found such a method by pressing modifier keys while dragging, as it works in most other applications. If it's not possible, what would you recommend me how I could handle this scenario efficiently with Lightroom? I had thought about using flags or labels, but they'll affect the source image, not just the instance within the collection.