US presidential contenders fight for minority votes
Democratic US presidential hopefuls fighting for black voters have been seeking an edge in South Carolina as Republicans criss-crossed the state for a path out of Donald Trump's long shadow.
Hillary Clinton stepped up her hammering of Democrat rival Bernie Sanders for what she said were his false claims about President Barack Obama's legacy.
Prominent black leaders echoed the theme - an effort to use the first African-American president as a wedge between Mr Sanders and black voters.
"He has called the president weak, a disappointment," Mrs Clinton said of Mr Sanders at a forum in Denmark. "He does not support, the way I do, building on the progress the president has made."
In the wake of her bruising rout in New Hampshire, the former US secretary of state hopes the first-in-the-south primary will showcase her strength with at least one core segment of the Democratic coalition.
A Democrat cannot win the nomination, much less the White House, without significant backing and enthusiasm from black communities.
For Republicans, South Carolina is another chance to emerge as the viable alternative to Mr Trump, the billionaire reality TV star who snatched the race away from the Republican establishment.
Although he appears to have a solid lead in the polls in the state, the rest of the field is hoping to peel off support from the large and influential evangelical community.
As his rivals hustled through rare snowfall, Mr Trump showed he would not make it easy and was able to steal the spotlight with a Twitter threat to sue his closest competitor.
"If @TedCruz doesn't clean up his act, stop cheating, & doing negative ads, I have standing to sue him for not being a natural born citizen," Mr Trump wrote.
Another tweet questioned Mr Cruz's faith, saying: "How can Ted Cruz be an evangelical Christian when he lies so much and is so dishonest?"
Mr Trump's broadside was a response to cutting new ads shown by the Cruz campaign in South Carolina.
Jeb Bush and his allies also are aiming attacks on the bomb-throwing front-runner, hoping his coarse style and record on social issues will turn off voters.
Right To Rise USA, the super political action committee backing Mr Bush, released an attack ad blasting Mr Trump for supporting partial-birth abortion, allegedly defrauding students of Trump University and trying "to seize private property to line his own pockets".
Mr Bush campaigned at a faith forum at conservative Bob Jones University in Greenville, where he mused about what his famous father, former president George Bush senior, would think of Mr Trump's cursing.
"I can't imagine my dad ... ," Mr Bush said, trailing off as the audience laughed.
Mr Bush has embraced his family's network in the state. He is inviting his brother, former president George W Bush, to campaign with him.
On Friday, he picked up the endorsement of South Carolina's former first lady Iris Campbell, a long-time Bush family ally.
Mr Trump was the only Republican to bypass South Carolina on Friday, redirecting his typically unconventional campaign to Florida, where he was holding a rally in Tampa.
On the Democratic side, Mrs Clinton's attacks on Mr Sanders were backed up by the Congressional Black Caucus PAC.
Mr Sanders wants to "undo" Mr Obama's accomplishments, said PAC chairman and congressman Gregory Meeks, pointing to Mr Sanders' past criticism of the president and his 2011 suggestion that Democrats should mount a primary challenge to Mr Obama.
"I believe Senator Sanders' disparaging comments towards the president are misplaced, misguided, and do not give credit where credit is due," the New York Democrat said.
Mr Sanders says he has been largely supportive of Mr Obama, despite his occasional critique.
"Last I heard, a United States senator had the right to disagree with the president, including a president who has done such an extraordinary job," Mr Sanders said in Thursday night's debate.
Mr Clinton has significantly bulked up her campaign advertising plan, reaching well beyond the next two states in the state-by-state voting to decide who will represent each party in the November general election.
She has an eye on the March 1 "Super Tuesday" contests and now plans to air ads in 17 additional states, including Texas, Minnesota and Georgia.
Former Virginia governor Jim Gilmore, meanwhile, ended his campaign after failing to win support. The Republican said he would support the party's nominee.