Prince Ali bin al Hussein has been reprimanded by the head of FIFA's ad-hoc electoral committee for speaking about a rival candidate ahead of Friday's vote.
Prince Ali of Jordan is standing for election alongside Sheikh Salman bin Ibrahim al Khalifa of Bahrain, UEFA general secretary Gianni Infantino, South Africa's Tokyo Sexwale and Jerome Champagne, a former FIFA deputy secretary general from France.
Sheikh Salman, the Asian Football Confederation president, is the favourite to succeed Blatter, who first became FIFA president in 1998.
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Conservative MP Damian Collins on Tuesday raised questions over Sheikh Salman's election as AFC president in 2013 and said the Government should not support any bids by the Football Association to host FIFA tournaments if the Bahraini is elected president of football's world governing body.
Sheikh Salman issued a firm denial to the latest allegations and Prince Ali declined to comment, having received a disciplinary letter from Domenico Scala, the man in charge of the procedure for Friday's election for comments made earlier this month.
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Prince Ali had questioned the role of Sheikh Salman in the Bahrain uprising of 2011. Sheikh Salman has denied any involvement in the torture and imprisonment of pro-democracy demonstrators in Bahrain in 2011.
Prince Ali said on Wednesday: "I am not going to comment on any other candidate. In fact, I was cautioned by the chairman of the electoral committee that I should not be commenting when I answered some very legitimate questions before.
"What I'm focused on is the election itself. I'm very optimistic and happy with the way things are going."
Prince Ali described the reprimand as belonging to "old FIFA".
He added: "That's the old FIFA. I'm wanting to change that."
Prince Ali is seeking reassurances over the voting procedure for the election and the use of transparent polling booths to answer his concerns.
Voters reportedly documented how they had voted in last May's presidential election, which Blatter won ahead of Prince Ali before resigning days later, prompting this week's extraordinary congress and Friday's presidential vote at Hallenstadion, Zurich.
FIFA had dismissed Prince Ali's plea to use the transparent polling booths, but now football's world governing body has been asked to explain its reasons by the Court of Arbitration for Sport, which will issue a ruling on the expedited process by Thursday morning.
FIFA has not otherwise engaged in the process, so it remains possible CAS could call for the vote to be postponed.
FIFA, which is this week expected to approve wide-scale reforms to ensure openness and guard against the corruption which has engulfed it in recent times, insists it is sufficient for delegates from the 207 voting nations - Kuwait and Indonesia are suspended - to hand over cameras and mobile phones before entering the booths.
Prince Ali's legal representatives are seeking clarification on the enforcement of those measures and what sanctions are available for any violation of the ban by delegates after being less than satisfied by the response received from FIFA's ad-hoc electoral committee.
Six of the transparent voting booths arrived in Zurich on Wednesday.
"I figured instead of people saying it's too late to get it done, we'd help them out in the process," Prince Ali added.
"It is a very legitimate concern and it's also common sense. You need to give people the right and the freedom to vote how they want when it's a secret ballot."
Prince Ali was adamant he would continue in the election, even if CAS dismisses his complaint, which was pursued after a response was received to his initial concerns at the beginning of February.
"I'm in there until the end," he added.
"I'm fighting for football. I'm not fighting for anything else."
FIFA's executive committee met on Wednesday, with acting president Issa Hayatou speaking on its behalf in calling for the reforms to be voted in on Friday.
Hayatou said: "The eyes of the world are on us this week after one of the most challenging times in our history. The approval of the reforms will send a strong message that we have listened and that we are taking the action necessary to regain trust and improve our performance.
"Each of these measures is critical for the future of FIFA and global football. We urge each of the member associations to support the reforms in full, and then to implement them in their entirety at home. It is a collective responsibility we have for football."
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