US President Barack Obama presents Jody Lewen, Executive Director of the Prison University Project at San Quentin State Prison in California, with the 2015 National Humanities Medal for the organization during a ceremony in the East Room of the White House in Washington, DC, September 22, 2016. / AFP PHOTO / SAUL LOEBSAUL LOEB/AFP/Getty Images

US President Barack Obama presents Jody Lewen, Executive Director of the Prison University Project at San Quentin State Prison in California, with the 2015 National Humanities Medal for the organization during a ceremony in the East Room of the White House in Washington, DC, September 22, 2016. / AFP PHOTO / SAUL LOEBSAUL LOEB/AFP/Getty Images

WASHINGTON, DC - SEPTEMBER 22: Senate Minority Leader Harry Reid (D-NV) (2nd R) is joined by Senate Finance Committee members Sen. Debbie Stabenow (D-MI), Sen. Ron Wyden (D-OR) and Sen. Ben Cardin (D-MD) call on Republicans to hold a vote on the Presidential Tax Transparency Act at the U.S. Capitol September 22, 2016 in Washington, DC. The proposed legislation would require presidential candidates to 'release their tax returns shortly after becoming the official nominees of their parties.' (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - SEPTEMBER 22: Senate Minority Leader Harry Reid (D-NV) (2nd L) is joined by (L-R) Sen. Ron Wyden (D-OR), Sen. Ben Cardin (D-MD) and Sen. Chris Murphy (D-CT) to call on Republicans to hold a vote on the Presidential Tax Transparency Act at the U.S. Capitol September 22, 2016 in Washington, DC. The proposed legislation would require presidential candidates to 'release their tax returns shortly after becoming the official nominees of their parties.' (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - SEPTEMBER 22: Sen. Chris Murphy (D-CT) speaks during a news conference with Senate Finance Committee members (L-R) Sen. Debbie Stabenow (D-MI), Sen. Ron Wyden (D-OR), Sen. Ben Cardin (D-MD) and Senate Minority Leader Harry Reid (D-NV) to call on Republicans to hold a vote on the Presidential Tax Transparency Act at the U.S. Capitol September 22, 2016 in Washington, DC. The proposed legislation would require presidential candidates to 'release their tax returns shortly after becoming the official nominees of their parties.' (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - SEPTEMBER 22: Senate Minority Leader Harry Reid (D-NV) is joined by Sen. Chris Murphy (D-CT) and Senate Finance Committee members Sen. Debbie Stabenow (D-MI), Sen. Ron Wyden (D-OR) and Sen. Ben Cardin (D-MD) call on Republicans to hold a vote on the Presidential Tax Transparency Act at the U.S. Capitol September 22, 2016 in Washington, DC. The proposed legislation would require presidential candidates to 'release their tax returns shortly after becoming the official nominees of their parties.' (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - SEPTEMBER 22: Senate Finance Committee members (L-R) Sen. Debbie Stabenow (D-MI), Sen. Ron Wyden (D-OR) and Sen. Ben Cardin (D-MD) hold a news conferene to call on Republicans to hold a vote on the Presidential Tax Transparency Act at the U.S. Capitol September 22, 2016 in Washington, DC. The proposed legislation would require presidential candidates to 'release their tax returns shortly after becoming the official nominees of their parties.' (Photo by Chip Somodevilla/Getty Images)

US President Barack Obama presents journalist and author Isabel Wilkerson with the 2015 National Humanities Medal during a ceremony in the East Room of the White House in Washington, DC, September 22, 2016. / AFP PHOTO / SAUL LOEBSAUL LOEB/AFP/Getty Images