The English Rugby Football Union believes the competition should be expanded to allow relegation and promotion between two divisions.
Teams such as Germany, Portugal, Spain and Georgia could be among those invited to join.
The RFU outlined the idea on Tuesday as it published its eight-year-plan for the future of the game in England.
RFU management board chairman Brian Baister said: "The Six Nations tournament is the best and most vibrant in the world.
"But at the moment everything is focused on the top end of the competition in terms of who wins.
"So we thought how much more exciting it would be if attention could also be focused on the bottom end in terms of who was going to be relegated.
"That would mean creating a second tier which we believe would help develop the game in Europe enormously."
RFU chief executive Francis Baron said the RFU also hoped there would be further Cup competitions for clubs in the future.
?We are hopeful that in eight years time we have two Cup competitions in Europe,? he told sportbusiness.com
English rugby officials will put forward plans for a Six Nations Championship with 12 teams with emerging European nations forming a second division.
