US President Barack Obama will travel to Copenhagen to support the bid by Chicago to host the 2016 Olympic Games.
He'll join his wife, Michelle, in the Danish capital at the weekend.
Chicago faces opposition from Madrid, Rio de Janeiro and Tokyo in the vote.
Brazilian, Spanish and Japanese leaders are also expected to lobby IOC delegates at the meeting.
The impact of star personalities on Olympic bids has been demonstrated when lobbying by former Britain Prime Minister Tony Blair in 2005 helped London win the 2012 Games, and Russian President Vladimir Putin led Sochi's bid for the 2014 Winter Olympics in 2007.