House of Representatives speaker Paul Ryan said of Donald Trump: “I think conservatives want to know: does he share our values and our principles.” Photograph: Jonathan Ernst/Reuters

Paul Ryan, the Republican speaker of the House of Representatives, has said that he is “not ready” to endorse Donald Trump as his party’s presidentia(...)

Republican US presidential candidate and businessman Donald Trump waves  to supporters

Donald Trump’s vow to round up and deport all of America’s undocumented immigrants if he is elected president could shrink the economy by around 2 per(...)

Donald Trump and Hillary Clinton: on some foreign policy issues, it’s Hillary the Hawk against Donald the Quasi-Dove. Photographs: Damon Winter/Zach Gibson/The New York Times

It seems odd, in this era of gender fluidity, that we are headed toward the most stark X versus Y battle since Billie Jean King and Bobby Riggs. Donal(...)

Supporting Donald Trump at the California Republican Convention in Burlingame, California on Friday. Photograph: Stephen Lam/Reuters

Deal-maker Donald Trump, the self-declared presumptive Republican presidential nominee, is negotiating his way to the election in November on a simple(...)

Republican US presidential hopeful Ohio Governor John Kasich celebrates his Ohio primary victory. Photograph: AFP

After a critical win on his home turf, Ohio Governor John Kasich begins a new phase of his long-shot presidential campaign that his aides hope will ul(...)

Republican presidential candidate hopefuls Donald Trump and Ted Cruz  greet each following a debate sponsored by on March 3rd, 2016 in Detroit, Michigan. Photograph: Chip Somodevilla/Getty Images

Republican presidential hopeful Ted Cruz split victories in four nominating contests with front-runner Donald Trump on Saturday, bolstering Mr Cruz’s (...)

Republican presidential candidate, former Florida govenor Jeb Bush accompanied by his wife Columba, speaks at his South Carolina Republican presidential primary rally in Columbia. Mr Bush has quit the presidential race. Photograph: AP

Before Donald Trump’s put-downs and the stumbles in presidential debates, and before the profound frustration of voters became so unmistakably appare(...)

People sit on the rubble of a damaged building after air strikes by pro-Syrian government forces in the rebel held al-Qaterji neighbourhood of Aleppo, Syria, on Sunday. Photograph:  Abdalrhman Ismail/Reuters

US president Barack Obama on Sunday urged Russia to stop bombing “moderate” rebels in Syria in support of its ally Bashar al-Assad, a campaign seen in(...)

Republican candidate Donald Trump and Democratic candidate Bernie Sanders. Photographs: Reuters

Billionaire Donald Trump and socialist Bernie Sanders won their New Hampshire primary elections, the second contest in the US presidential race, in vi(...)

US Republican presidential hopeful Donald Trump speaks to the crowd during a rally on Monday in Manchester, New Hampshire. Photograph: Don Emmert/AFP/Getty Images

Donald Trump raised eyebrows at his final rally before the New Hampshire primary by repeating a vulgar slur shouted from the crowd about a rival candi(...)