WASHINGTON, DC - JUNE 24: Speaker of the House Paul Ryan (R-WI) speaks during news conference to introduce the House Republicans' tax reform proposal in the Rayburn Room at the U.S. Capitol June 24, 2016 in Washington, DC. House Ways and Means Committee Chairman Kevin Brady (R-TX) said that the GOP wants to 'bust up' the Internal Revenue Service, get rid of the estate tax and create a tax code so simple that Americans can file on a postcard-sized form. (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - JUNE 24: Speaker of the House Paul Ryan (R-WI) answers reporters' questions during news conference to introduce the House Republicans' tax reform proposal in the Rayburn Room at the U.S. Capitol June 24, 2016 in Washington, DC. House Ways and Means Committee Chairman Kevin Brady (R-TX) said that the GOP wants to 'bust up' the Internal Revenue Service, get rid of the estate tax and create a tax code so simple that Americans can file on a postcard-sized form. (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - JUNE 24: Speaker of the House Paul Ryan (R-WI) arrives for a news conference to introduce the House Republicans' tax reform proposal in the Rayburn Room at the U.S. Capitol June 24, 2016 in Washington, DC. Brady said that the GOP wants to 'bust up' the Internal Revenue Service, get rid of the estate tax and create a tax code so simple that Americans can file on a postcard-sized form. (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - JUNE 24: Speaker of the House Paul Ryan (R-WI) speaks during news conference to introduce the House Republicans' tax reform proposal in the Rayburn Room at the U.S. Capitol June 24, 2016 in Washington, DC. House Ways and Means Committee Chairman Kevin Brady (R-TX) said that the GOP wants to 'bust up' the Internal Revenue Service, get rid of the estate tax and create a tax code so simple that Americans can file on a postcard-sized form. (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - JUNE 24: Speaker of the House Paul Ryan (R-WI) arrives for a news conference to introduce the House Republicans' tax reform proposal in the Rayburn Room at the U.S. Capitol June 24, 2016 in Washington, DC. Brady said that the GOP wants to 'bust up' the Internal Revenue Service, get rid of the estate tax and create a tax code so simple that Americans can file on a postcard-sized form. (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - JUNE 24: Reporters are reflected in a mirror as they attend a news conference where House Republicans introduced their tax reform proposal in the Rayburn Room at the U.S. Capitol June 24, 2016 in Washington, DC. House Ways and Means Committee Chairman Kevin Brady (R-TX) said that the GOP wants to 'bust up' the Internal Revenue Service, get rid of the estate tax and create a tax code so simple that Americans can file on a postcard-sized form. (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - JUNE 24: Speaker of the House Paul Ryan (R-WI) (C) addresses a news conference to introduce the House Republicans' tax reform proposal with House Ways and Means Committee Chairman Kevin Brady (R-TX) (5th L) and House Majority Whip Steve Scalise (R-LA) (3rd L) in the Rayburn Room at the U.S. Capitol June 24, 2016 in Washington, DC. Brady said that the GOP wants to 'bust up' the Internal Revenue Service, get rid of the estate tax and create a tax code so simple that Americans can file on a postcard-sized form. (Photo by Chip Somodevilla/Getty Images)

(FILES) This file photo taken on June 8, 2016 shows Democratic Presidential Candidate Bernie Sanders during A Future to Believe In rally in Washington, DC. Bernie Sanders said June 24, 2016 he will vote for Hillary Clinton in the US presidential election in November, bowing to his former rival for the White House but stopping short of a full endorsement.Asked on MSNBC whether he would cast his ballot for Clinton, the Vermont senator who waged a surprisingly tough campaign during the primaries said, "Yes." / AFP PHOTO / MOLLY RILEYMOLLY RILEY/AFP/Getty Images