It could become clear this week who the Republican and Democratic presidential nominees will be.

Twelve states will hold primary elections or caucuses Tuesday, called "Super Tuesday." In most of those states, public opinion studies show Republican Donald Trump and Democrat Hillary Clinton have much more support than other candidates.

Last week, Trump said people "are so tired of these politicians -- all talk, no action. We are going to make America great again. We are going to win, win, win."

Republican candidates said they will try to stop or at least slow Trump's campaign.

Senator Marco Rubio said "Trump will never be the Republican nominee. We are not going to let the conservative movement, and the party of Ronald Reagan and the party of Abraham Lincoln be taken over by a first-rate con artist."

Trump answered that Rubio has not won any caucuses or primary elections. He said Rubio is hated in his home state of Florida.

Clinton has also criticized Trump. After she defeated Senator Bernie Sanders in the South Carolina primary Saturday by almost 50 points, she said, "we do not need to make America great again. America has never stopped being great. But we do need to make America whole again. Instead of building walls, we need to be tearing down barriers."

Senator Sanders says his campaign against Hillary Clinton is not over. He said "the middle class of this country has been shrinking and almost all new income and wealth has been going to the top one percent."

I'm Mario Ritter.

VOA Washington Correspondent Michael Bowman reported this story from Washington. Christopher Jones-Cruise adapted the story for VOA Learning English. Kathleen Struck was the editor.