Confirmation on the details of European club rugby's new elite tournament remains on hold but an announcement could be made as early as Friday.
It had been thought an announcement would be made on Thursday, but it could now be Friday or early next week.
A new 20-team competition is expected to see six Aviva Premiership teams, six clubs from France's Top 14 competition and seven of the RaboDirect PRO12 sides qualify for a competition that would succeed the Heineken Cup.
The final place would be decided after a play-off between this season's seventh-placed finishers in the Premiership and Top 14.
Press Association Sport understands an agreement is very close, and once signed all parties can then chase a resolution between broadcasters BT Sport and Sky, both of whom have indicated a willingness to agree a compromise TV rights deal.
The Six Nations committee is expected to provide the basis of the new governing body, with some existing European Rugby Cup staff retained.