The 209 members of Fifa are to vote for their new president at a congress in Zurich, as football’s world governing body faces a major corruption scandal.
Sepp Blatter, the favourite, is seeking a fifth term. He is being challenged by Prince Ali bin al-Hussein of Jordan.
The vote comes two days after seven top officials were held in Zurich in a US fraud inquiry that indicted 14 people.
Opening the second day of the congress, Mr Blatter told delegates Fifa faced “troubled times”.
Mr Blatter has been called on to quit but has already made clear he is not responsible for the scandal and wants to combat corruption.
“Events have thrown a shadow across Fifa and congress. Let’s try to lift that shadow,” he said.
“Let’s show to the world that we are able to run this institution that is Fifa, that we can do that together.”
Proceedings were briefly disrupted by two Palestinian demonstrators calling for Israel to be excluded from Fifa. They were ejected from the hall.
Mr Blatter, 79, and Prince Ali, 39, will each have 15 minutes to address the delegates.
The 209 member football associations then vote individually in the ballot, which is secret.
In the first round, a candidate must get 140 votes – two-thirds – to win outright.
If that is not achieved, there will be a second round requiring a simple majority – whoever gets the most votes.
Mr Blatter, in office for 17 years, enjoys strong support in Asia, the Americas and Africa and is thought likely to win another four-year term.
The president of the Nigerian Football Federation, Amaju Pinnick, told the BBC he was 100% convinced Mr Blatter would win, taking “a minimum” of 50 of the 54 African votes.
“We know our friends from Asia, our friends from Latin America, so I can assure you it’s going to be a good victory for him.”
Prince Ali has the support of most of Europe.
Responding to the scandal, he said that Fifa needed leadership that “accepts responsibility for its actions and does not pass blame… and restores confidence in the hundreds of millions of football fans around the world”.
He said: “I am a straightforward person with straightforward ideas and ethics – a person who loves our sport.”
BBC sports correspondent Alex Capstick, who is outside the congress, says Prince Ali may not win but is making inroads and could give Mr Blatter “a bloody nose”.
The head of European football’s governing body, Uefa, Michel Platini, has called for Mr Blatter to go.
Two criminal investigations were announced on Wednesday.
The US investigation accuses those indicted of bribery, racketeering and money-laundering involving tens of millions of dollars over 24 years since 1991.
It includes allegations of bribes to influence the outcome of bids to stage football tournaments such as the 2010 World Cup in South Africa and the 2016 Copa America in the US.
Former Fifa vice president Jack Warner, who was among those indicted, spent a night in jail in Trinidad before his release on bail of $395,000 (£258,000). He was greeted by cheering supporters.
Fifa vice president Jeffrey Webb, also arrested on Thursday, has now been “provisionally dismissed” as head of the Confederation of North, Central American and Caribbean Association Football (Concacaf).
Swiss prosecutors have launched a separate investigation into the bidding process for the World Cup tournaments in 2018 in Russia and 2022 in Qatar.
Many of Fifa’s major sponsors have expressed concern over the investigations.
Coca-Cola, Visa, Adidas, McDonald’s, Hyundai Motor and Budweiser are pressing Fifa to take immediate action to restore its reputation.
Even the UN, which has partnerships with Fifa, said it was “watching what’s going on in Zurich and other places very carefully”. – BBC Report