The 2026 World Cup will take place in Canada, Mexico and the USA
The expanded 48-team competition in the United States, Mexico and Canada was due to feature 16 groups of three.
But the excitement generated by last year's tournament in Qatar, when some groups went down to tense final games, has caused Fifa to rethink.
Confirmation of the move could come at the governing body's council meeting in Rwanda on 16 March.
BBC Sport understands there is agreement among all parties that the four-team format should be retained, providing it does not extend the 'footprint' of the competition - which includes preparation time as well as the tournament itself.
"Groups of three sounded great but there are some issues," Concacaf president Victor Montagliani told the FT Business of Football Summit.
"Is it right that you qualify for a World Cup and a third of teams go home after two games?
"We do have to be responsible. There was a footprint of days for 2014 and 2018 and we can't go over that. We can't have a three-month World Cup."
Moving to groups of four would expand the competition from its projected 80 matches to a possible 104.
While the tournament would have to take place over a longer period, it is felt cutting preparation for teams - from nearly three weeks before Russia 2018, although not quite as drastically as the week they had before Qatar 2022 - would mean players were not on duty for a greater length of time.
The move is also bound to raise environmental concerns given more teams will have to travel and Montagliani says that issue is being taken seriously.
"The match schedule is very important," he said. "You can't have teams travelling from New York to Los Angeles.
"Teams will play in pods. There will be a group playing out of Boston, Philadelphia and New York. Another one in Vancouver and Seattle and another in LA and San Francisco.
"There are other strategies that have to be applied as well so we adhere to what is put in the bid."
-- Courtesy of BBC Sport