The initial bid was fronted by Andretti co-founder Michael Andretti, a former Indycar and F1 driver, and billed as an Andretti entry with backing from GM’s Cadillac brand. GM had said it would build its own engine by 2028.
The new plan is for GM to enter as a team owner, while its commitment to building its own power-unit by 2028 would remain.
That would mean the new team would still need to buy customer engines from an existing supplier to plug the gap from 2026 onwards.
It is not clear which brand GM would use for the project.
Another key difference is that Michael Andretti no longer has any managerial role in the team he co-founded.
It was announced in September that Towriss had taken control of Andretti and that Michael Andretti had moved into an ambassadorial role.
Michael Andretti was considered by many in F1 as a divisive figure who had rubbed people up the wrong way with what was seen to be his confrontational approach to trying to secure an entry.
F1 is facing an investigation from the US department of justice into its decision to reject Andretti’s initial entry.
Mercedes F1 boss Toto Wolff said in Las Vegas on Thursday: “If a team can add to the championship, particularly if GM decides to come in as a team owner, that is a different story.
“And as long as it is creative, that means we’re growing the popularity of the sport, we’re growing the revenue of the sport, then no team will ever be against it. So I’m putting my hope in there.”
Ferrari team boss Frederic Vasseur said: “The discussion is between FIA, the team and F1. It’s not our choice.
“For sure, if it’s good for the sport, good for the show, good for business, and adds value on the sporting side, we are all OK.”