Corbyn will probably win the NEC vote tomorrow. Only two of the CLP reps, the Young Labour rep, two of three PLP reps (if George Howarth has not replaced Dennis Skinner yet, in which case Skinner is still on), Glennis Willmott (MEP rep), Jon Ashworth, Keith Vaz (
"THE MOST CORRUPT MINISTER IN RECENT YEARS"), James Asser, Tom Watson, the two Councillors (one might vote for Corbyn being on the ballot though) and the USDAW trade union rep are opposed to Corbyn. 17 is the magic number, assuming full turnout.
What the moderates are banking on is that some trade union reps are unable to get time off to attend or that some grow a pair and rebel (more likely to happen if a secret ballot is used). I'm not sure, but some Corbynists might also be under investigation by the compliance unit, so they may not be able to attend. Labour Party's rulebook is complicated.
EDIT: Two trade union reps are also on holiday apparently. 15 is the magic number now if they don't fly back quickly and considering the moderates in total number about 13, plus assuming that some other trade union reps are unable to attend (somewhat probable as many live outside London) or some rebel, they might just edge it. Wouldn't necessarily count on it.