The 2012 Olympic Stadium is set to be named on Thursday as one of four stadiums put forward by London as host venues for England's 2018 World Cup bid - but that will not end the debate over its future.

The stadium is expected to be named along with Wembley, Arsenal's Emirates Stadium and Tottenham's new White Hart Lane - but only subject to its final capacity meeting FIFA's requirements of a minimum of 40,000 seats.

London 2012's plan has always been to reduce the Olympic Stadium to 25,000 seats after the Games and keep it as a national venue for elite athletics.

That has provoked a fierce debate about the stadium being a potential drain on council tax-payers in the capital, and London mayor Boris Johnson is keen for a football or rugby club to ease the burden by making the stadium their permanent home.

The Olympic Stadium's inclusion as a potential World Cup venue would, however, be subject to the ground having another long-term sporting use.

Even if the stadium is eventually rejected, it would be used in any World Cup as a training facility with the Olympic Park as a huge fan-park.

Thursday marks the deadlines for candidate cities to submit their bids to England 2018.

Portsmouth pulled out of the contest, leaving 15 cities - containing 21 stadia - expected to submit applications. Between 12 and 18 stadiums from about 10 cities will be chosen on December 16 to form part of England's candidate file to be submitted to FIFA in May. FIFA's vote on the World Cup hosts takes place in early December 2010.

Portsmouth City Council refused to provide the necessary financial guarantees to Fratton Park, fearing it was too much of a risk.

The club had put forward a plan to redevelop the ground to a 37,000-seat stadium, with additional temporary seats to bring capacity up to more than 40,000.

An England 2018 spokesman expressed sadness and surprise at the decision but said bid leaders were confident of a strong array of potential host cities.

The spokesman said: "Naturally, we are disappointed at Portsmouth's withdrawal from the process. Along with the other cities involved, Portsmouth had shown great enthusiasm for the project and the council's decision not to approve their application at this stage is a surprising and sad outcome.

"The host city process still has an extremely strong candidate list and we are confident we have an array of cities, stadiums and general facilities that will support an exceptional bid to FIFA next May."

The hopeful cities expected to submit their applications tomorrow to become a host venue are Birmingham, Bristol, Derby, Hull, Leeds, Leicester, Liverpool, London, Manchester, Milton Keynes, Newcastle-Gateshead, Nottingham, Plymouth, Sheffield and Sunderland.

The bids from Manchester, Liverpool and Sheffield are expected to be for two stadia in the city, and London's for four.