Vocal Speaker Conversation hindered by Recorded Backup Noise

Hello

I am stuck. In the past I could remove very difficult background noise using Audition tools. In this sample presented I am unable to remove the noises sufficiently enough to render the vocals listenable. I have used spectral to isolate the noise - no success. A hard limit started out promising however once I sampled the noise and proceeded to use Noise Reduction the results were undesirable.

Please advise if there is a remedy using the available tools in Audition CS6.

Thanks!