CLEVELAND, OH - JULY 21: Dressed as George Washington, Jeff Christensen (R) poses for a selfie with Arizona delegate John Rosadoon prior to the start of the fourth day of the Republican National Convention on July 21, 2016 at the Quicken Loans Arena in Cleveland, Ohio. Republican presidential candidate Donald Trump received the number of votes needed to secure the party's nomination. An estimated 50,000 people are expected in Cleveland, including hundreds of protesters and members of the media. The four-day Republican National Convention kicked off on July 18. (Photo by Chip Somodevilla/Getty Images)

CLEVELAND, OH - JULY 21: Dressed as George Washington, Jeff Christensen walks the floor prior to the start of the fourth day of the Republican National Convention on July 21, 2016 at the Quicken Loans Arena in Cleveland, Ohio. Republican presidential candidate Donald Trump received the number of votes needed to secure the party's nomination. An estimated 50,000 people are expected in Cleveland, including hundreds of protesters and members of the media. The four-day Republican National Convention kicked off on July 18. (Photo by Jeff Swensen/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: 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