US politics

Sheriffs on horseback and police break up a group of demonstrators outside Republican U.S. presidential candidate Donald Trump's campaign rally in Costa Mesa

Mike Blake/Reuters

Sheriffs on horseback and police break up a group of demonstrators outside Republican U.S. presidential candidate Donald Trump’s campaign rally in Costa Mesa, California.

Donald Trump, president and chief executive of Trump Organization Inc. and 2016 Republican presidential candidate, center, speaks during a campaign event in New York

John Taggart/Bloomberg

Carlos Barria/Reuters

Republican U.S. presidential candidate Donald Trump’s hand is seen as he reacts during a campaign event in Harrisburg, Pennsylvania

Hillary Clinton...Democratic presidential candidate Hillary Clinton arrives at a campaign stop, Wednesday, April 20, 2016, in Philadelphia. (AP Photo/Matt Rourke)

Matt Rourke/AP

Democratic presidential candidate Hillary Clinton arrives at a campaign stop in Philadelphia 

Hillary Clinton...A Secret Service Agent stands guard as Democratic presidential candidate Hillary Clinton speaks at the Corsi senior center, Friday, April 15, 2016, in New York. (AP Photo/Mary Altaffer)

Mary Altaffer/AP

A Secret Service Agent stands guard as Democratic presidential candidate Hillary Clinton speaks at the Corsi senior center, in New York

Low-Wage Workers Strike And Rally For $15 Wage In Chicago...CHICAGO, IL - APRIL 14:  Demonstrators demanding an increase in the minimum wage to $15-dollars-per-hour prepare to march in the streets on April 14, 2016 in Chicago, Illinois. The demonstrators marched to and protested in front of several locations during a day-long effort to draw attention to low-wage jobs. The demonstration was one of about 300 scheduled to take place nationwide today.  (Photo by Scott Olson/Getty Images)

Scott Olson/Getty

Demonstrators demanding an increase in the minimum wage to $15-dollars-per-hour prepare to march in the streets on Thursday in Chicago, Illinois. The demonstrators marched to and protested in front of several locations during a day-long effort to draw attention to low-wage jobs 

A man takes a photograph of the stage before a campaign event featuring Republican presidential candidate Donald Trump at St. Norbert College in De Pere, Wisconsin, USA

Patrick Semansky/AP

A man takes a photograph of the stage before a campaign event featuring Republican presidential candidate Donald Trump at St. Norbert College in De Pere, Wisconsin, USA

Tim Ferris shades himself from the sun while waiting in line to attend a campaign rally with Democratic presidential candidate, Sen. Bernie Sanders, in Kissimmee, Florida, USA

Phelan M. Ebenhack/AP

Tim Ferris shades himself from the sun while waiting in line to attend a campaign rally with Democratic presidential candidate, Sen. Bernie Sanders, in Kissimmee, Florida, USA

Marco Rubio...Republican presidential candidate, Sen. Marco Rubio, R-Fla., poses for photographs during a campaign rally in Hialeah, Fla., Wednesday, March 9, 2016. (AP Photo/Paul Sancya)

Paul Sancya/AP

Republican presidential candidate, Senator Marco Rubio, poses for photographs during a campaign rally in Hialeah, Florida 

Barack Obama...President Barack Obama meets with members of his economic team in the Roosevelt Room of the White House in Washington, Friday, March 4, 2016. Obama spoke about U.S. employers adding 242,000 workers in February, driving another solid month for the resilient American job market.

Pablo Martinez Monsivais/AP

President Barack Obama meets with members of his economic team in the Roosevelt Room of the White House in Washington. Obama spoke about U.S. employers adding 242,000 workers in February, driving another solid month for the resilient American job market 

Elise Amendola/AP

Voters cast ballots at a polling station for Massachusetts’ primary election, as Super Tuesday starts in North Andover, Mass USA

Hillary Clinton...Democratic presidential candidate Hillary Clinton gestures during a commercial break at a CNN town hall style televised event at the University of South Carolina School of Law, in Columbia, S.C., Tuesday, Feb. 23, 2016. (AP Photo/Gerald Herbert)

  © Gerald Herbert/AP

Democrat presidential candidate Hillary Clinton gestures during a commercial break at a CNN town hall televised event at the University of South Carolina School of Law, in Columbia, US

Mike Nelson / EPA

Supporters of US Republican presidential candidate businessman Donald Trump at a rally in Las Vegas, Nevada

Demonstrators protesting for an increase in the minimum wage enter the media file center at the PBS NewsHour Democratic presidential candidate debate at the University of Wisconsin-Milwaukee

Win McNamee/Getty Images

Demonstrators protesting for an increase in the minimum wage enter the media file center at the PBS NewsHour Democratic presidential candidate debate at the University of Wisconsin-Milwaukee

President Barack Obama returns a salute as he boards Air Force One before his departure from Andrews Air Force Base, Maryland. USA

Pablo Martinez Monsivais/AP

President Barack Obama returns a salute as he boards Air Force One before his departure from Andrews Air Force Base

Win McNamee/Getty

Democratic presidential candidate, Sen. Bernie Sanders addresses supporters after winning the New Hampshire Democratic primary in Concord, New Hampshire. Sanders defeated Democratic presidential candidate Hillary Clinton in the first-in-the-nation primary

New Hampshire Residents Vote In The First-In-The-Nation New Hampshire Primary...A resident, right, hands an election official a Republican ballot at the town hall polling site during the New Hampshire presidential primary election in Harts Location, New Hampshire, U.S., on Tuesday, Feb. 9, 2016. According to the New Hampshire Secretary of State's office, the state has 383,834 voters who haven't declared a party affiliation, compared to 260,896 registered Republicans and 229,202 Democrats. Photographer: Andrew Harrer/Bloomberg

Andrew Harrer/Bloomberg

A resident, right, hands an election official a Republican ballot at the town hall polling site during the New Hampshire presidential primary election in Harts Location, New Hampshire, U.S., on Tuesday. According to the New Hampshire Secretary of State’s office, the state has 383,834 voters who haven’t declared a party affiliation, compared to 260,896 registered Republicans and 229,202 Democrats.

Presidential Candidate Marco Rubio Holds Retail Campaign Stops...An image of Senator Marco Rubio, a Republican from Florida and 2016 presidential candidate, is seen on his campaign bus as it sits outside the building which houses his campaign headquarters in Manchester, New Hampshire, U.S., on Monday, Feb. 8, 2016. Rubio, who surged to second place in polls after coming in third in the Iowa caucuses, spent Sunday trying to extinguish a political brushfire after he delivered the same canned answer three times within a matter of minutes at Saturday's presidential debate. Photographer: Daniel Acker/Bloomberg

Daniel Acker/Bloomberg

An image of Senator Marco Rubio, a Republican from Florida and 2016 presidential candidate, is seen on his campaign bus as it sits outside the building which houses his campaign headquarters in Manchester, New Hampshire, U.S 

Marco Rubio Campaigns Ahead Of New Hampshire Primary...NASHUA, NH - FEBRUARY 08:  Republican presidential candidate Sen. Marco Rubio (R-FL) sips coffee before doing a television interview at Norton's Classic Cafe during a campaign stop February 8, 2016 in Nashua, New Hampshire. Rubio is hoping for a good showing on Tuesday when people in New Hampsire head to the polls in the 'First in the Nation' presidential primary.  (Photo by Chip Somodevilla/Getty Images) **BESTPIX**

Chip Somodevilla/Getty

Republican presidential candidate Sen. Marco Rubio sips coffee before doing a television interview at Norton’s Classic Cafe during a campaign stop in Nashua, New Hampshire

Democratic Presidential Candidates Hillary Clinton And Bernie Sanders Debate In Durham, New Hampshire...DURHAM, NH - FEBRUARY 04:  Democratic presidential candidates former Secretary of State Hillary Clinton walks on stage during a break as she debates with U.S. Sen. Bernie Sanders (I-VT) during their MSNBC Democratic Candidates Debate at the University of New Hampshire on February 4, 2016 in Durham, New Hampshire. This is the final debate for the Democratic candidates before the New Hampshire primaries.  (Photo by Justin Sullivan/Getty Images)

Justin Sullivan/Getty

Democratic presidential candidate Hillary Clinton walks on stage during a break as she debates with U.S. Sen. Bernie Sanders (I-VT) during their MSNBC Democratic Candidates Debate at the University of New Hampshire in Durham, New Hampshire. This is the final debate for the Democratic candidates before the New Hampshire primaries