Cape Town - World Rugby has reportedly given its Six Nations and Rugby Championship member unions an extra week to consider the Nations Championship concept.
According to BBC Sport, World Rugby had set a deadline of Friday for formal expressions of interest from the unions.
But it is understood this will not be enforced so more discussions can take place.
Scheduled to launch in 2022, the Nations Championship would see a top division of 12 teams from both hemispheres play each other once in a calendar year, either through traditional competitions like the Six Nations or an enlarged Rugby Championship, or in summer or autumn Test windows.
The top two teams would then meet in an end-of-year showpiece final.
The Daily Mail reports that a hard deadline of May 21 - the date of World Rugby’s next council meeting - has been set for plans to be universally ratified.
Should the unions still not agree to the plans by then, the concept could fall through entirely.
There are also talks that the Nations Championship would be underpinned by a second division made up of current tier-two nations, who would be given the chance of promotion against the Nations Championship’s bottom-placed team.