First Lady Michelle Obama campaigns for Democratic presidential candidate Hillary Clinton at George Mason University September 16, 2016 in Fairfax, Virginia. / AFP / ZACH GIBSON

US First Lady Michelle Obama campaigns for Democratic presidential candidate Hillary Clinton at George Mason University on September 16, 2016 in Fairfax, Virginia. / AFP / ZACH GIBSON

US First Lady Michelle Obama greets supporters as she campaigns for Democratic presidential candidate Hillary Clinton at George Mason University on September 16, 2016, in Fairfax, Virginia. / AFP / ZACH GIBSON

First lady Michelle Obama waves during a campaign rally in support of Democratic presidential candidate Hillary Clinton and vice presidential candidate, Sen. Tim Kaine, D-Va., Friday, Sept. 16, 2016, at George Mason University in Fairfax, Va. (AP Photo/Manuel Balce Ceneta)

First lady Michelle Obama speaks during a campaign rally in support of Democratic presidential candidate Hillary Clinton and vice presidential candidate Sen. Tim Kaine, D-Va., Friday, Sept. 16, 2016, at George Mason University in Fairfax, Va. (AP Photo/Manuel Balce Ceneta)

First lady Michelle Obama speaks during a campaign rally in support of Democratic presidential candidate Hillary Clinton and vice presidential candidate Tim Kaine, D-Va., Friday, Sept. 16, 2016, at George Mason University in Fairfax, Va. (AP Photo/Manuel Balce Ceneta)