WASHINGTON, DC - JULY 21: President Barack Obama speaks to Muslims gathered at an Eid al-Fitr reception in the East Room at the White House July 21, 2016 in Washington, DC. (Photo by Mark Wilson/Getty Images)

WASHINGTON, DC - JULY 21: President Barack Obama speaks to Muslims gathered at an Eid al-Fitr reception in the East Room at the White House July 21, 2016 in Washington, DC. (Photo by Mark Wilson/Getty Images)

WASHINGTON, DC - JULY 21: People hold up their cellphones while President Barack Obama speaks to Muslims gathered at an Eid al-Fitr reception in the East Room at the White House July 21, 2016 in Washington, DC. (Photo by Mark Wilson/Getty Images)

(FILES) This file photo taken on June 29, 2016 shows US Senator Elizabeth Warren, Democrat of Massachusetts, speaking in Washington, DC. US Democratic presidential candidate Clinton is expected to reveal her vice presidential pick by July 23, 2016, when she campaigns in Florida. The feisty senator is a liberal superstar who can help transfer the Sanders allegiance to Clinton. Warren has developed a reputation for ripping into Trump at every opportunity. / AFP PHOTO / SAUL LOEBSAUL LOEB/AFP/Getty Images

(FILES) This file photo taken on March 18, 2015 shows US Agriculture Secretary Tom Vilsack speaking at a press conference in Washington, DC on March 18, 2015. US Democratic presidential candidate Clinton is expected to reveal her vice presidential pick by July 23, when she campaigns in Florida. Vilsack has known the Clintons for decades, and the candidate is said to have deep trust in him. A native of Pittsburgh, he could help carry the crucial swing state of Pennsylvania. / AFP PHOTO / NICHOLAS KAMMNICHOLAS KAMM/AFP/Getty Images

(FILES) This file photo taken on January 21, 2016 shows US Labor Secretary Tom Perez speaking in Washington, DC. US Democratic presidential candidate Clinton is expected to reveal her vice presidential pick by July 23, when she campaigns in Florida. One of the true liberals on the shortlist, Perez could rally core Democrats and heal the rift with leftwing supporters of Clinton's former nomination rival Bernie Sanders. As a Latino in the cabinet, he could cement the increasingly important Hispanic vote. / AFP PHOTO / Nicholas KammNICHOLAS KAMM/AFP/Getty Images

WASHINGTON, DC - JULY 21: U.S. President Barack Obama (C) holds a jersey given to him by the MLB 2015 World Series Champion Kansas City Royals during an event to honor them for their winning season last year at the White House July 21, 2016 in Washington, DC. (Photo by Mark Wilson/Getty Images) *** BESTPIX ***

US President Barack Obama shows a jersey presented to him by Kansas City Royals Manager Ned Yost (R) during an event honoring 2015 World Series champions the Kansas City Royals on July 21, 2016 in the East Room of the White House in Washington, DC. / AFP PHOTO / MANDEL NGANMANDEL NGAN/AFP/Getty Images