U.S. President Barack Obama waves to reporters as he walks out with First lady Michelle Obama from the White House in Washington, U.S. August 6, 2016 before departure for their summer vacation in Martha's Vineyard, Massachusetts. REUTERS/Yuri Gripas

U.S. President Barack Obama and first lady Michelle Obama wait for the arrival of Singapore Prime Minister Lee Hsien Loong and his wife Mrs. Lee Hsien Loong at the White House in Washington U.S., August 2, 2016. REUTERS/Mary F. Calvert

(FILES) This file photo taken on August 3, 2016 shows US President Barack Obama speaking at the Presidential Summit of the Mandela Washington Fellowship for Young African Leaders in Washington, DC. President Barack Obama will visit Laos next month, a first for a US president, in a trip that begins with a G20 summit in China, the White House said August 18, 2016. The September 2-9 tour will be the president's 11th visit to Asia since he took office in 2009. / AFP PHOTO / Brendan SmialowskiBRENDAN SMIALOWSKI/AFP/Getty Images

U.S. President Barack Obama waves to reporters as he walks out with First lady Michelle Obama from the White House in Washington, U.S. August 6, 2016 before departure for their summer vacation in Martha's Vineyard, Massachusetts. REUTERS/Yuri Gripas

Charles Grassley (R-IA) presides over a hearing on U.S. immigration enforcement policies, on Capitol Hill in Washington July 21, 2015. REUTERS/Jonathan Ernst

WASHINGTON, DC - AUGUST 17: Former NAACP President and CEO Kweisi Mfume speaks at a news conference on what would have been the 129th birthday of prominent Pan-Africanism movement advocate Marcus Garvey at the National Press Club August 17, 2016 in Washington, DC. The family of Marcus Garvey has recently petitioned the Department of Justice and White House counsel requesting a posthumous presidential pardon on the political leader's conviction in 1923 for mail fraud in the U.S.. (Photo by Alex Wong/Getty Images)

WASHINGTON, DC - AUGUST 17: Melvin Footo, CEO and president of Constituency for Africa, speaks at a news conference on what would have been the 129th birthday of prominent Pan-Africanism movement advocate Marcus Garvey at the National Press Club August 17, 2016 in Washington, DC. The family of Marcus Garvey has recently petitioned the Department of Justice and White House counsel requesting a posthumous presidential pardon on the political leader's conviction in 1923 for mail fraud in the U.S.. (Photo by Alex Wong/Getty Images)

WASHINGTON, DC - AUGUST 17: Former NAACP President and CEO Kweisi Mfume speaks at a news conference on what would have been the 129th birthday of prominent Pan-Africanism movement advocate Marcus Garvey at the National Press Club August 17, 2016 in Washington, DC. The family of Marcus Garvey has recently petitioned the Department of Justice and White House counsel requesting a posthumous presidential pardon on the political leader's conviction in 1923 for mail fraud in the U.S.. (Photo by Alex Wong/Getty Images)