In the USA, ten Democrats have taken part in a TV debate.
Elizabeth Warren, a Massachusetts senator who has been surging in opinion polls, asked "Who is this economy really working for? It's doing great for a thinner and thinner slice at the top."
Warren said: "We need to make structural change in our government, in our economy and in our country."
Warren supports replacing private medical insurance with government-run healthcare.
New York Mayor Bill de Blasio backed her on healthcare.
Ohio congressman Tim Ryan insisted the US must stay "completely engaged" in the Middle East.
Tulsi Gabbard, an anti-war Hawaii congresswoman, hit back: "Is that what you will tell the parents of those two soldiers who were just killed in Afghanistan?"
Tulsi Gabbard of Hawaii is standing as the anti-war candidate, because she’s been to war a lot of times and she’s seen war firsthand and realized that it, in fact, is bad.
New Jersey Senator Cory Booker was the only candidate who did not raise his hand when asked whether he would sign back on to the 2015 Iran nuclear deal as it was originally negotiated under the Obama administration.
Bernie Sanders, a Democratic socialist, is promising a "political revolution", including free healthcare for all and paying off America's $1.6tn (£1.25tn) student debt mountain.