Secretary Jack Lew stands in his office at the U.S. Department of the Treasury in Washington, D.C., on Wednesday. Ariel Zambelich/NPR hide caption

itoggle caption Ariel Zambelich/NPR

Sen. Marco Rubio, R-Fla., speaks at a Sept. 18 forum for GOP presidential candidates in Greenville, S.C., hosted by Heritage Action for America. Sean Rayford/Getty Images hide caption

itoggle caption Sean Rayford/Getty Images

Iranian President Hassan Rouhani prepares to speak with NPR's Steve Inskeep on Saturday in New York. Rouhani reaffirmed Iran's commitment to the nuclear deal and said his country would be willing to discuss Syria's future with the United States — after ISIS is defeated. Bryan Thomas for NPR hide caption

itoggle caption Bryan Thomas for NPR