Challenging Trump

Protestors hold signs protesting against Republican presidential hopeful Donald Trump outside the venue where Trump is the key note speaker at the Republican Party Lincoln Day event in Birch Run, Michigan August 11, 2015. REUTERS/Rebecca Cook

People protest outside the Luxe Hotel, where Donald Trump was expected to speak in Brentwood, Los Angeles, California, United States July 10, 2015. REUTERS/Lucy Nicholson

Two Mexican-American Vietnam veterans protest against words spoken about veterans by Donald Trump outside the venue where Trump is the key note speaker at the Republican Party Lincoln Day event in Birch Run, Michigan, August 11, 2015. REUTERS/Rebecca Cook

A group of women protest against Donald Trump outside the venue where Trump is the key note speaker at the Republican Party Lincoln Day event in Birch Run, Michigan, August 11, 2015. REUTERS/Rebecca Cook

A girl participates in a protest calling for businesses to sever their relationships with Donald Trump over his recent comments about Mexican immigrants as they demonstrate outside the site of a new hotel owned by Trump at the Old Post Office Building in Washington, July 9, 2015. REUTERS/Yuri Gripas

A protester is interviewed outside the airport as he awaits the arrival of Donald Trump, in Laredo, Texas July 23, 2015. REUTERS/Rick Wilking

A protester who did not want to be named awaits the arrival of Donald Trump to speak with local residents as he tours the museum and birthplace of actor John Wayne while campaigning in Winterset, Iowa June 27, 2015. REUTERS/Brian Frank� �

A group of Mexican-Americans protest against Donald Trump outside the venue where Trump is the key note speaker at the Republican Party Lincoln Day event in Birch Run, Michigan, August 11, 2015. REUTERS/Rebecca Cook

A man protests with a Donald Trump pinata in a trash can outside the Luxe Hotel, where Donald Trump was expected to speak in Brentwood, Los Angeles, California, United States July 10, 2015. REUTERS/Lucy Ni

A woman holds a protest sign as she drives past the Luxe Hotel, where Donald Trump was expected to speak in Brentwood, Los Angeles, California, United States July 10, 2015. REUTERS/Lucy Nicholson

A group of Mexican-Americans protest against Donald Trump outside the venue where Trump is the key note speaker at the Republican Party Lincoln Day event in Birch Run, Michigan, August 11, 2015. REUTERS/Rebecca Cook

Protesters gather outside the airport, awaiting the arrival of Donald Trump, in Laredo, Texas July 23, 2015. REUTERS/Rick Wilking

People protest outside the Luxe Hotel, where Donald Trump was expected to speak in Brentwood, Los Angeles, California, United States July 10, 2015. REUTERS/Lucy Nicholson

Nancy Rosales Hernandez, 23, protests outside the Luxe Hotel, where Donald Trump was expected to speak in Brentwood, Los Angeles, California, United States July 10, 2015. REUTERS/Lucy Nicholson

Women hold protest signs as they drive past the Luxe Hotel, where Donald Trump was expected to speak in Brentwood, Los Angeles, California, United States July 10, 2015. REUTERS/Lucy Nicholson

Protesters call for businesses to sever their relationships with Donald Trump over his recent comments about Mexican immigrants as they demonstrate outside the site of a new hotel owned by Trump at the Old Post Office Building in Washington July 9, 2015. REUTERS/Yuri Gripas

People protest outside the Luxe Hotel, where Donald Trump was expected to speak in Brentwood, Los Angeles, California, United States July 10, 2015. REUTERS/Lucy Nicholson