FIFA presidential candidate Jerome Champagne made a formal complaint claiming two rivals supported by continental governing bodies will have an unfair advantage at the vote on Friday.
Champagne urged FIFA election monitors on Monday to cancel 20 extra passes for "observers" from UEFA and seven for the Asian Football Confederation to enter the election hall in Zurich.
In a letter seen by The Associated Press, he wrote that UEFA and the AFC plan "to swamp the Congress hall with confederation employees able to access" voters.
UEFA general secretary Gianni Infantino and AFC President Sheikh Salman are seen as front-runners in the five-candidate contest. The other candidates are former FIFA vice-president Prince Ali of Jordan, and South African businessman Tokyo Sexwale.
Champagne, who has run his own campaign, said allowing extra accreditations would "betray a gross violation of the principle of fairness."
"Moreover, the list of names of the persons benefiting from these accreditations reveals the presence of most of the members of these two candidates' campaign teams," wrote the French former diplomat, who was ousted from his job as FIFA international relations director in 2010.
Despite 11 years working as a FIFA insider under Sepp Blatter, Champagne has seemed like an outsider in a campaign that includes two members of Middle East monarchies, a commodities tycoon, and the spending power of wealthy European soccer.
Champagne promised to pursue his complaint against "these unfair and undue privileges" if the three-member FIFA election panel did not act by Tuesday.
"The question of the accreditation is in the hands of FIFA," the election committee said in a statement.
Potential breaches of FIFA election rules can be appealed to the Court of Arbitration for Sport.
The vote of up to 209 FIFA member federations on Friday will choose a successor to Blatter, as FIFA aims to renew itself after the biggest corruption crisis in its 112-year history.