Try the sticky sheets (can't remember specific name). We got these to keep Jax from scratching up Bruce's speaker and monitors in the studio. They have really helped.
With it being on the floor what you might want to do is put the sticky sheet (you can buy them at most pet stores) on a large piece of cardboard and place it in front of the door when you are not home or in bed. That way it is easy to move when you need to.
When I purchased my sticky sheets the cashier told me he did this with his cat because his cat was darting out the door every time it opened. You should be able to eventually remove the sticky sheets and the cat will stay away. We haven't removed them from the speakers yet. I should try it and see what he does.

Good luck!! I hope you can figure something out besides declawing or getting rid of him.