A group aiming to keep the Oakland Raiders NFL American football franchise in California has submitted a formal stadium plan to the league.

The Associated Press news agency, citing a person familiar with the deal, reported that the plan was submitted by the Fortress Investment Group within the past 10 days.

The Raiders are hoping to relocate to Las Vegas, and plans have already been approved by Nevada authorities for a new $1.9bn (£1.5bn/€1.8bn) stadium in the city.

Last month, the team lost one of its key backers for the project, Sheldon Adelson, chairman of the Las Vegas Sands Corporation. Adelson had been set to provide $650m towards the project but he withdrew his support after the Raiders submitted a proposed lease agreement worth just $1 in peppercorn rent to the Las Vegas Stadium Authority. The proposal did not include the Adelson family.

The team insisted that it would be able to make up the extra funds, but the relocation is far from certain.

Should the Raiders remain in Oakland, the team could end up playing in a new stadium developed by Fortress. The stadium would be built on the site of the Raiders’ current home, the Coliseum.

The group behind the plan is being led by NFL Hall of Famer Ronnie Lott and former Raiders quarterback Rodney Peete. The plan centres on a $1.3bn stadium that includes $350m in public funds.

Under initial plans, the investment group will put forward $400m for the project, with the Raiders and the NFL to provide $500m between them, and the city $200m for infrastructure. Oakland would also provide 100 acres of land worth $150m.