Sepp Blatter has been warned by FIFA not to attempt to backtrack on his pledge to quit as president.
Domenico Scala, who is overseeing the presidential election, said that a leadership change was an essential component of the far-reaching reforms required to overhaul FIFA amid deepening criminal investigations into soccer corruption.
Mr Scala's blunt comments came after Swiss newspaper 'Schweiz am Sonntag' reported Mr Blatter is considering trying to retain the presidency after support from Africa and Asia.
Mr Blatter announced on June 2 - only four days after being re-elected for a fifth term - that he would stand down from the post after a successor was chosen sometime between December and February.
Mr Scala, head of FIFA's audit and compliance committee, is urging Mr Blatter not to consider back-tracking on that pledge. The 79-year-old Blatter has already reneged on a 2011 promise to leave office in 2015.
"For me, the reforms are the central topic," Mr Scala said. "That is why I think it is clearly indispensable to follow through with the initiated process of leadership change as it has been announced."
The FIFA executive committee will meet in Zurich on July 20 to set the election date. EU MEPs last week voted on a resolution calling for Mr Blatter to speed up his announced resignation and let FIFA appoint an interim leader.
Mr Scala set out the election process at FIFA headquarters on June 2, directly after Mr Blatter's sudden resignation statement, and said significant work was required to "regain the trust of the public," including imposing term limits for the president.
Mr Blatter has been portraying himself as leading that reform process, via his Twitter account and in FIFA's internal media outlets.