The US President Barack Obama will be in Copenhagen later this week to support Chicago's bid to stage the 2016 Olympic Games.
A personal appearance by Obama, the first by a sitting U.S. president at an IOC session, could potentially play a crucial role in swaying votes by International Olympic members who must choose between Chicago, Madrid, Rio de Janeiro and Tokyo.
Spain's King Juan Carlos, and the Brazilian president and Japan's new Prime Minister will also be in Copenhagen for the outcome of a contest seen by Olympic observers as one of the closest ever, with no clear front runner, and all four bids capable of succeeding.
Each of the cities will make a presentation on Friday night to the IOC's 115 members who will cast their votes the same day.
