Sepp Blatter says he will resign as president of football's governing body Fifa amid a corruption scandal.
In announcing his exit, the 79-year-old Swiss has called an extraordinary Fifa congress "as soon as possible" to elect a new president.
Blatter was re-elected last week, despite seven top Fifa officials being arrested two days before the vote as part of a US prosecution.
But he said: "My mandate does not appear to be supported by everybody."
Blatter, who has been Fifa president since 1998, said: "The next ordinary Fifa congress will take place on 13 May, 2016 in Mexico City.
"This would create unnecessary delay and I will urge the executive committee to organise an extraordinary congress for the election of my successor at the earliest opportunity.
"This will need to be done in line with Fifa's statutes and we must allow enough time for the best candidates to present themselves and to campaign."
The extraordinary congress is expected to take place between December 2015 and March 2016.
Fifa was rocked last week by the arrests on charges of racketeering, wire fraud and money laundering as part of a US prosecution that also indicted 14 people.
The latest allegations of corruption to emerge on Tuesday involved reports claiming Fifa general secretary Jerome Valcke was responsible for an alleged $10m payment of bribes over South Africa's bid to host the 2010 World Cup.
A separate criminal investigation by Swiss authorities into how the 2018 and 2022 World Cups were allocated is also under way.