According to a poll of Conservative members on Conservativehome, Cameron's popularity has been slipping. Amongst the 1700 Conservative members polled, he has slipped to plus 49%, down from plus 59% in July.
It should be remembered that these are Conservative members and are therefore far more likely to be positive about the party leadership. It is still a healthy plus percentage but the point is it is moving downwards.
This reflects the Yougov poll on 21st July that saw Cameron's ratings amongst the electorate generally slip from plus 28 to plus 12 percent. This is not the stuff that makes for the massive swing the Conservatives need to win a general election outright.