On Saturday, former Secretary of State Hillary Clinton defeated Vermont Senator Bernie Sanders in the Nevada Democratic caucuses.
Political experts say the clear win in Nevada was a big relief for Clinton and her supporters. They say Sanders must prove he can win more than the youth vote, and in states more diverse than New Hampshire.
Sanders said he believes that when Democrats hold their convention in Philadelphia in July, voters will see "one of the great political upsets in the history of the United States."
Republicans in South Carolina
Also on Saturday, Donald Trump won the Republican primary in South Carolina. Marco Rubio and Ted Cruz tied for second.
Trump's victory in the New Hampshire primary last week and his win Saturday strengthen his place as Republican front-runner.
Trump repeated parts of his campaign speech, saying the United States will start "winning again" if he becomes president. He said he will make Mexico pay for a wall along the U.S. southern border. He said he will challenge China on its trade surplus.
Nevada holds its Republican primary on February 23. Many states will hold primaries on March 1, a day known as Super Tuesday. Super Tuesday usually shows who will likely win the party nomination and compete for president of the United States.
Former Florida governor Jeb Bush told a crowd in South Carolina that he was ending his campaign for the presidency. At the beginning of the presidential race, many believed Bush would be the Republican nominee.
I'm Jonathan Evans.