Washington - Only five Republicans were left in the race for the White House Sunday, and frontrunner Donald Trump hammered home the idea that he is the only one who could defeat Democrat Hillary Clinton in November.
Trump's victory lap came after his resounding win on Saturday in the South Carolina primary - a contest that helped whittle down the field when former Florida governor Jeb Bush called time on his White House bid.
Clinton defeated rival Bernie Sanders in the Nevada Democratic caucuses on Saturday, but their duel looks set to last, with the former secretary of state's campaign showing some weaknesses, especially among young voters.
"Nobody is unstoppable," Trump told CNN, even paying tribute to Bush - who he repeatedly savaged on the campaign trail - as "very capable."
"I have some advantages but it will be hard," the 69-year-old billionaire businessman told NBC's "Meet the Press."
'Crazier things happen'
Speaking from Palm Beach, Florida, where he owns a resort, Trump made the rounds of the Sunday political talk shows, repeating that his Republican presidential rivals - especially Senators Ted Cruz and Marco Rubio - were formidable foes.
"He's very talented," the real estate tycoon told CNN. "And certainly he could beat me, and so could Marco, and so could the others that are running. You know, crazier things happen in the world of politics."
But he insisted he did not think the race would come down to a so-called brokered Republican convention in July - a situation in which none of the candidates has an absolute majority of nominating delegates.
So far, according to the New York Times, Trump has 61 delegates, while Cruz has 11 and Rubio has 10. A total of 1 237 are needed to win the nomination.
Trump made the case that he could be the consensus candidate.
"I'll bring over a lot of Democrats, bring over a lot of independents," he said on CNN, audaciously predicting that he could even win largely Democratic New York state in the November 8 general election.
"If I win New York, the election's over," he said.
"If it's Hillary against me, that's going to be a tremendous turnout. I'm going to win."
Rubio, who is 25 years his junior and a first-term senator from Florida, finished in second place in South Carolina on Saturday, edging out Cruz. He says he intends to show voters that Trump is all style and no substance.
"If you're running to be president of the United States, you can't just tell people you're going to make America great again," Rubio told CBS News's "Face the Nation," citing Trump's campaign slogan.
He specifically cited Trump's favourable view of Russian President Vladimir Putin as worrisome.
Cruz questioned Trump's conservative bona fides, noting his formerly progressive views on social issues such as abortion.
The road to Super Tuesday
The Clinton camp was breathing a collective sigh of relief Sunday after her victory in Nevada by five percentage points - 52.7% to 47.2% for Sanders. It was a needed rebound after her loss in New Hampshire.
So far, according to The New York Times, she has 502 delegates to 70 for the senator from Vermont thanks to 451 "superdelegates" - Democratic party heavyweights who vote at the convention but who are not bound by the results of any primary.
Black voters helped Clinton win in Nevada, and she will need their support again in South Carolina, which holds its Democratic primary on February 27 and which in 2008 had a Democratic electorate that was 55% African American.
"I want to knock down all the barriers holding people back," the 68-year-old Clinton told CNN in an interview aired Sunday.
That is one of her stock campaign messages - she has talked at length on the trail about the need to address racism and economic disparities in American society. She says Sanders's message is too vague and won't fix problems.
But the 74-year-old self-described democratic socialist emphasizes that his popularity is not limited to any one community and is grounded in young voters - of all races.
"We have a lot of work to do," he admitted Sunday on CBS, but added: "I think as people become familiar with my ideas, we are going to do better and better."
Sanders has his sights set on Super Tuesday - March 1, when 18% of Democratic delegates will be up for grabs in a dozen US states and territories.