WASHINGTON, DC - SEPTEMBER 19: (L-R) Sen. Rand Paul (R-KY), Center for the National Interest Vice Chairman Dov Zakheim and Sen. Chris Murphy discuss legislation to halt the sale of some weapons to Saudi Arabia at the center September 19, 2016 in Washington, DC. After the Department of Defense announced the sale of $1.5 billion of arms to Saudi Arabia, Senators Paul, Murphy, Al Franken (D-MN) and Mike Lee (R-UT) are attempting to block the sale by using a provision of the Arms Export Control Act of 1976 that "provides for special procedures whereby a senator can force a vote on an arms sale by the president." (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - SEPTEMBER 19: Sen. Rand Paul (R-KY) (L) and Center for the National Interest Vice Chairman Dov Zakheim discuss legislation to halt the sale of some weapons to Saudi Arabia at the center September 19, 2016 in Washington, DC. After the Department of Defense announced the sale of $1.5 billion of arms to Saudi Arabia, Senators Paul, Murphy, Al Franken (D-MN) and Mike Lee (R-UT) are attempting to block the sale by using a provision of the Arms Export Control Act of 1976 that "provides for special procedures whereby a senator can force a vote on an arms sale by the president." (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - SEPTEMBER 19: (L-R) Sen. Rand Paul (R-KY), Center for the National Interest Vice Chairman Dov Zakheim and Sen. Chris Murphy sit at the head of the table to discuss legislation to halt the sale of some weapons to Saudi Arabia at the center September 19, 2016 in Washington, DC. After the Department of Defense announced the sale of $1.5 billion of arms to Saudi Arabia, Senators Paul, Murphy, Al Franken (D-MN) and Mike Lee (R-UT) are attempting to block the sale by using a provision of the Arms Export Control Act of 1976 that "provides for special procedures whereby a senator can force a vote on an arms sale by the president." (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - SEPTEMBER 19: (L-R) Sen. Rand Paul (R-KY), Center for the National Interest Vice Chairman Dov Zakheim and Sen. Chris Murphy discuss legislation to halt the sale of some weapons to Saudi Arabia at the center September 19, 2016 in Washington, DC. After the Department of Defense announced the sale of $1.5 billion of arms to Saudi Arabia, Senators Paul, Murphy, Al Franken (D-MN) and Mike Lee (R-UT) are attempting to block the sale by using a provision of the Arms Export Control Act of 1976 that "provides for special procedures whereby a senator can force a vote on an arms sale by the president." (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - SEPTEMBER 19: Sen. Chris Murphy (D-CT) participates in a discussion about legislation to halt the sale of some weapons to Saudi Arabia at the Center for the National Interest September 19, 2016 in Washington, DC. After the Department of Defense announced the sale of $1.5 billion of arms to Saudi Arabia, Senators Murphy, Rand Paul (R-KY), Al Franken (D-MN) and Mike Lee (R-UT) are attempting to block the sale by using a provision of the Arms Export Control Act of 1976 that "provides for special procedures whereby a senator can force a vote on an arms sale by the president." (Photo by Chip Somodevilla/Getty Images)

NEW YORK, NY - SEPTEMBER 19: (L-R) Senior Associate Editor, The Washington Post, Lally Graham Weymouth, Director, Sylvester Comprehensive Cancer Center, University of Miami, Dr. Stephen Nimer, Chief Scientific Officer for Immunobiology, Eli Lilly & Company, Dr. Michael Kalos, Chief of the Melanoma, President and Chief Executive Officer, St. Jude Children's Research Hospital, Dr. James R. Downing and Immunotherapeutics Service Memorial Sloan-Kettering Memorial Cancer Center, Dr. Jedd Wolchok speak at the 2016 Concordia Summit - Day 1 at Grand Hyatt New York on September 19, 2016 in New York City. (Photo by Ben Hider/Getty Images for Concordia Summit)

NEW YORK, NY - SEPTEMBER 19: (L-R) Senior Associate Editor, The Washington Post, Lally Graham Weymouth, Director, Sylvester Comprehensive Cancer Center, University of Miami, Dr. Stephen Nimer, Chief Scientific Officer for Immunobiology, Eli Lilly & Company, Dr. Michael Kalos, Chief of the Melanoma, President and Chief Executive Officer, St. Jude Children's Research Hospital, Dr. James R. Downing and Immunotherapeutics Service Memorial Sloan-Kettering Memorial Cancer Center, Dr. Jedd Wolchok speak at the 2016 Concordia Summit - Day 1 at Grand Hyatt New York on September 19, 2016 in New York City. (Photo by Ben Hider/Getty Images for Concordia Summit)

NEW YORK, NY - SEPTEMBER 19: (L-R) Senior Associate Editor, The Washington Post, Lally Graham Weymouth, Director, Sylvester Comprehensive Cancer Center, University of Miami, Dr. Stephen Nimer, Chief Scientific Officer for Immunobiology, Eli Lilly & Company, Dr. Michael Kalos, Chief of the Melanoma, President and Chief Executive Officer, St. Jude Children's Research Hospital, Dr. James R. Downing and Immunotherapeutics Service Memorial Sloan-Kettering Memorial Cancer Center, Dr. Jedd Wolchok speak at the 2016 Concordia Summit - Day 1 at Grand Hyatt New York on September 19, 2016 in New York City. (Photo by Ben Hider/Getty Images for Concordia Summit)