Donald Trump won another state in his effortto become the Republican Party nominee for president.He earned 46 percent of the vote in the Nevada caucus.Florida Senator Marco Rubio won 24 percent of the vote,and Texas Senator Ted Cruz came in third with 21 percent.Retired neurosurgeon Ben Carsonand Ohio Governor John Kasich were far behind.It is Trump's third win in a row after winning primaries in New Hampshireand South Carolina earlier this month.Trump said he is now "winning the country,"and he will pick up more Republican supportersas his rivals drop out of the race.The next big test for Trump and the other candidates is March 1.That day is called "Super Tuesday."More than 10 states will hold primaries and caucuses that day.By then, the Republican nomination processwill be almost one-third over.A candidate needs at least 1,237 delegatesin order to earn the party's nominationheading into the election in November.A poll of voters by CNNshowed Trump had supporters across most demographic groups.Trump said he was happy he was the top vote-getteramong Hispanic voters in the caucus.He has support even though he said he wants to build a wallbetween Mexico and the United States.He said he wants Mexico to pay for it.Matt Dallek is an assistant professor at George Washington University'sGraduate School of Political Management.He says some important questions emerge after Trump's winning streak."Where can he be stopped? Where is he deprived of a victory– or multiple victories – and who will do the stopping?"The answer will become clearer next week.