Two members of FIFA's executive committee - Amos Adamu of Nigeria and Reynald Temarii of Tahiti - were provisionally suspended on Wednesday for 30 days by the ethics committee.
It is alleged they offered to sell their votes when approached by Sunday Times reporters posing as lobbyists for an American consortium.
FIFA general secretary Jerome Valcke said on Wednesday he expected the vote to go ahead on December 2, but football's governing body will have to act quickly and decisively to ensure it does.
England and Russia are bidding to host the 2018 World Cup along with joint bids from Spain/Portugal and Belgium/Netherlands while Japan, South Korea, Qatar, United States and Australia are candidates for 2022.
VOTING DILEMMA
*Voting rights are restricted to the 24 members of the FIFA executive committee. This compares to more than 100 voting members when the International Olympic Committee chooses venues for the Summer and Winter Olympics.
If Adamu and Temarii are expelled, it is unclear whether they would immediately be replaced - FIFA statutes dictate that regional confederations choose the executive committee members - or whether the vote would be reduced to 22.
Bidding nations may protest if the size of the already small electoral college is reduced still further.
FIFA officials on Wednesday did not want to discuss either scenario, saying it was premature.
"I'm not a prophet," head of the ethics committee Claudio Sulser said. "It's hard for me to answer, it depends on the evidence that is brought forward."
ETHICS COMMITTEE
*FIFA's ethics committee is relatively new, having been created in 2006.
Its first chairman was former British athlete Sebastian Coe while Sulser is a lawyer and former Swiss football international.
One of its main briefs is to keep watch over the bid process for 2018 and 2022.
The committee said it would produce a final verdict on Temarii and Adamu by mid-November.
"I think we can take a decision before December 2... probably between November 15 and 17," Sulser said.
POSSIBLE COLLUSION
*Two unnamed candidate nations will also be investigated for breaching rules on collusion.
FIFA has rules ban bidding nations from making agreements with each other, but collusion was something critics said could become a possibility when it was decided to choose two World Cup hosts at the same time.
The ultimate penalty could be disqualification of the offending bids, but FIFA on Wednesday were reluctant to discuss this possibility, saying there were numerous stages to pass before such a drastic measure might be taken.
