This refers to the standard policy of funding agencies/businesses, whereby none of them will publicly declare their contribution until a private "behind the scenes" agreement has been reached between all potential contributors to ensure that the total amount of funding needed for the project will in fact be reached.
No-one - least of all 'big household name sponsors' - will go public with an offer of funds without a prior guarantee that the target will be reached. No-one wants to be seen backing a 'loser'.

https://en.wikipedia.org/wiki/Cynicism_(contemporary)