West Ham remain committed to their bid to relocate to the Olympic Stadium despite the massive financial obligations that would ensue if they were to be successful.
The Hammers are one of four bidders hoping to be chosen as the new anchor tenant for the £486million Olympic Stadium, which has been vacant since hosting the closing ceremony to the Paralympics at the start of September.
Press Association Sport understands that West Ham are offering to pay a multi-million pound sum up front with investment of around £800million throughout the duration of the lease.
Reports earlier in the week suggested West Ham would be put off by having to make such a financial commitment but it is understood the club are still viewing the relocation to the Olympic Stadium as a priority and are fully committed to the investment required.
It is also understood that West Ham were surprised that the National Football League could now be in the mix for the tenure following reported talks with the London Legacy Development Corporation (LLDC) as the NFL are not one of the four bidders being considered in the competition process.
Mayor of London Boris Johnson, who is also chairman of the LLDC, is said to have had "encouraging" discussions with NFL officials over bringing more games to London after seeing games staged at Wembley Stadium once a year since 2007.
West Ham won the right to play at the Olympic Stadium last year, but the decision was nullified after protests from fellow bidders including Orient and Premier League rivals Tottenham, with the bidding process then re-opening.
The stadium will continue to be used to host athletic events, including the 2017 World Championships, as well as being available for community use.
When contacted by Press Association Sport, West Ham were unable to comment on the specifics of their bid due to confidentiality undertakings.