Franklin, Tennessee: Hillary Clinton acknowledged she has work to do in convincing voters that she has their best interests at heart, even as the former US secretary of state she savoured her weekend win over rival Democratic presidential candidate Bernie Sanders in the Nevada caucuses.
On the Republican side, US senators Marco Rubio and Ted Cruz battled to emerge as the true anti-Donald Trump candidate after the billionaire businessman's resounding victory in the South Carolina primary established him as the clear front-runner in the race for that party's presidential nomination.
Clinton was happy with her Nevada win but conceded that some voters are skeptical of her motivations.
"I think there's an underlying question that maybe is really in the back of people's minds and that is, you know, is she in it for us or is she in it for herself?" Clinton said on CNN. "I think that is a question that people are trying to sort through."
A large majority of black voters supported Clinton in Nevada, according to entrance polls, an outcome that bodes well for her in next Saturday's Democratic primary in South Carolina and on so-called Super Tuesday a few days later when primaries are held in several southern states where African-Americans make up a large segment of the Democratic electorate.
Working to increase his support among black voters, Sanders visited a Baptist church luncheon following services in West Columbia, South Carolina, and talked up the country's economic recovery under President Barack Obama.
Sanders, a Vermont senator, acknowledged that while his insurgent campaign has made strides, "at the end of the day ... you need delegates."
Sanders looked past South Carolina to list Colorado, Minnesota, Massachusetts and Oklahoma as places where he has a "good shot" to do well on 1 March, or Super Tuesday, which offers a large haul of delegates who will choose the party's nominee at the national convention in July.
As for Trump, he declined to say the Republican nomination was his to lose. But he quickly went on to declare, "I'm really on my way." Soon enough, in a television interview, he was toting up electoral math all the way through Election Day and concluding, "I'm going to win."
Trump's main rivals, Rubio and Cruz, used the Sunday morning news shows to spin optimistic scenarios after complete but unofficial returns in South Carolina put Trump way up on top, with Rubio squeaking past Cruz for second. But with roughly 70 percent of Republicans in national polls declining to back Trump, Cruz and Rubio tried to cast themselves as the one candidate around whom what Rubio calls the "alternative-to-Donald-Trump vote" can coalesce.
Rubio also took an aggressive run at Trump, faulting him for a lack of specifics on policy.
"If you're running for president of the United States, you can't just tell people you're going to make America great again," he said on CBS' Face the Nation, referring to Trump's campaign slogan.
At a later rally in Franklin, Tennessee, a Nashville suburb, Rubio took note of the smaller Republican field after former Florida Governor Jeb Bush's departure from the race, and celebrated his biggest crowd of the campaign, estimated at more than 3,000 people. Rubio avoided criticizing his Republican rivals, instead highlighting his efforts to help middle-class families.
Cruz, for his part, stressed his conservative bona fides and said he was the lone "strong conservative in this race who can win. We see conservatives continuing to unite behind our campaign," he told NBC's Meet the Press.
With Bush gone from the race, Rubio was hoping to pick off past donors to the Bush campaign and looking to benefit as well from a cessation in the millions of dollars in negative ads run against him by the Bush campaign and its allies.
Rubio also suggested it was only a matter of time before John Kasich and retired neurosurgeon Ben Carson ended their campaigns as well. The Florida senator hinted it would be better to get that winnowing over with, saying, "the sooner we can coalesce, the better we're going to be as a party in general."
Not so fast, Kasich countered. "We're getting big crowds everywhere we go," the Ohio governor insisted, listing Vermont, Massachusetts and Virginia as places he can shine.
Trump suddenly had nice things to say about Bush, the candidate he had hammered so relentlessly when they were rivals. As for Rubio, Trump told Fox News Sunday that "I start off liking everybody. Then, all of a sudden, they become mortal enemies."