Let the pitch begin.
She will be joined two days later by her husband, who is taking an unusual personal stake in the lobbying effort.
But so are the other heads of state involved. Chicago is locked in a tight race with Madrid, Rio de Janeiro and Tokyo for the games -- and the Obamas will face off against Brazilian President Luiz Inacio Lula da Silva; Spanish King Juan Carlos and Prime Minister Jose Luis Rodriguez Zapatero; and new Japanese Prime Minister Yukio Hatoyama.
Michelle Obama's plane landed a little before 11:30 a.m. local time, and she was greeted by a contingency that included Chicago Mayor Richard Daley, his wife, Maggie, Olympic gold medalist Jackie Joyner-Kersee and Chicago 2016 president Lori Healey.
She will spend the next two days meeting with International Olympics Committee members, hoping to persuade them to vote for her hometown. President Obama arrives Friday, and both Obamas will be part of Chicago's final presentation before the IOC in Copenhagen.
Obama would be the first U.S. president to take on such a direct role in lobbying for an Olympics event. His trip is expected to be brief, but some critics questioned whether it is appropriate for the president to hit pause on other pressing issues like health care reform and Iran's nuclear program to pitch his hometown.
The Associated Press contributed to this report.