A number of reports claim communications minister Lord Carter, who has supported the tie-up as a means to secure the future of Channel 4 as an alternative public service broadcaster to the BBC, will not be able to go into detail on it as the two sides have not yet agreed how it will work.
There is an uncertainty over which assets will be included in the joint venture and, according to the Daily Telegraph, its creation has been slowed by reaching a decision on who will run the company.
The line-up of the joint venture's assets is understood to be reliant on the attitude of the Treasury, which owns Channel 4 through the shareholder executive.
According to the Financial Times, the Treasury has become more reluctant to give Channel 4 permission to borrow money to buy assets, such as UKTV, the owner of TV channels such as Dave and Really.
It is hoped that UKTV could be brought within the joint venture by Channel 4 buying the 50% stake owned by Virgin Media to go with the 50% stake owned by BBC Worldwide.
The FT also reports that there are differences of opinion within the Channel 4 board, with some members apparently arguing that putting Channel 4's profitable digital channels into the joint venture was too risky.
It carries two quotes from sources close to discussions that indicate a deal is far from done. One is a BBC source, who said: "The two sides have got differences of opinion on the valuation of assets and on the way profits would be shard. There is still a very real possibility this will simply not happen."
The other source said: "There is no way a memorandum of understanding will be signed by Tuesday. That doesn't mean there won't be one at some time in the future and it could be soon but there are lots of things where we haven't reached agreement."
Tomorrow's report is likely to include a recommendation that part of the BBC's £3.4bn licence fee is diverted to fund independent producers making local news for ITV, a move which is meeting resistance from the BBC and BBC Trust.
The cash is to come from the £130m annual pot (running until 2012) that was earmarked to help the elderly make the switch from analogue to digital television.
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