The Trump campaign and Republican National Committee predicted Saturday that Biden's victory in the South Carolina primary will lead only to one result: a victory for President Donald Trump in November.

"After more than three decades of trying, Joe Biden finally won a presidential primary state, but this win does not equal momentum," RNC Chairwoman Ronna McDaniel said. "Today’s result all but guarantees that this primary process isn’t ending anytime soon. President Trump will beat whichever socialist the Democrats — eventually — nominate this November."

Trump campaign manager Brad Parscale said the president was the "clear winner" regardless of the result.

"The President will be running on his solid record of achievement for all Americans and will wipe the floor with whichever Democrat is unlucky enough to emerge," he said in a statement. "The South Carolina results just prove what a hot mess the Democrat primaries are, as the field once again descends into chaos heading into Super Tuesday. We don’t know who the eventual nominee will be, but they are all the same, and their radical big government socialist policies will be on the Democrat ballot in November no matter what.”

Democratic former Va. Gov. Terry McAuliffe endorsed Biden on CNN after NBC News projected him the winner of the South Carolina primary. 

McAuliffe, a well-known figure within the party, also strongly urged other candidates who have no realistic path forward to drop out. 

"I've thought long and hard about this," he said. "For me, it's about beating Donald Trump and to me it's an electability issue who has the best shot at beating Donald Trump." 

Virginia Sen. Tim Kaine, the 2016 vice presidential nominee, also endorsed Biden this week. This is an important boost for Biden's campaign as establishment Democrats line up behind the former vice president as he tries to get back his front-runner status from Sen. Bernie Sanders, I-Vt. The endorsement of Rep. James Clyburn, D-S.C., was also a factor in Biden's primary win. 

McAuliffe said that Biden will join him at an event in Norfolk, Va. on Sunday and believes Biden "has the best chance at winning Virginia in the general."  

South Carolina is the first contest in the race for the 2020 Democratic presidential nomination to feature a sizable share of black voters. Results from today’s NBC News Exit Poll find that the state’s black voters defy conventional stereotypes about Democrats being liberal, highly educated and nonreligious. 

More than half of black Democrats in South Carolina, 54 percent, say they are moderate or conservative — that’s nine points higher than whites in the state. A majority of black Democrats, 57 percent, in the state attend religious services at least weekly, a number nearly 30 points higher than among whites. And 28 percent of black Democrats in the state hold a college degree, compared to 58 percent of whites, according to the exit poll.

Based upon their reports of their previous voting activity, black voters show up to Democratic primaries on a regular basis. A total of 89 percent of black Democrats voting today said they’d voted before in a primary, compared to just 70 percent of white Democrats.

A new group of moderate Democrats trying to stop Bernie Sanders from winning their party’s presidential nomination is preparing to spend nearly $4 million hitting the Vermont senator in the final days before Super Tuesday, the group's executive director told NBC News.

Big Tent Project, which came together in recent weeks as some Democratic donors and operatives grew concerned about Sanders’ strength in Iowa and New Hampshire, has already spent about $1 million in Nevada and South Carolina on ads arguing Sanders is a radical who will lose to President Donald Trump.

Now, the group is quadrupling that amount to run digital ads and send mailers hitting Sanders in Virginia, Oklahoma, Arkansas, North Carolina, Texas, Minnesota, Massachusetts, and California, which all vote Tuesday.

"Big Tent Project is spending nearly $4 million on ads in Super Tuesday states to provide voters with the facts about Bernie Sanders radical record before they vote," said the group’s executive director, Jonathan Kott, a former top aide to West Virginia Democratic Sen. Joe Manchin.

One ad, which ran in Nevada and will now run again in Texas in both Spanish and English, accuses Sanders of allowing nuclear waste to be dumped near a poor Latino town in Texas (FactCheck.org calls the ad misleading). 

Another says "socialist Bernie Sanders" would lead to "another four years of Donald Trump."

The group is a 501(c)4 nonprofit organization, meaning it may never have to disclose its donors.

Joe Biden owes his off-the-ropes victory in the South Carolina Democratic presidential primary to the solid support he received from the state’s black, religious and moderate Democrats, according to the NBC News Exit Poll.

Biden was the overwhelming favorite of the state’s black Democrats: He received 60 percent of their votes. His performance among African Americans was far ahead of his nearest rival, Bernie Sanders, who got just 17 percent of the black vote.

NBC News projected Biden the winner as polls closed at 7 p.m. ET.

Biden also garnered the support of about half of voters who called themselves either moderate or conservative, and half of those attending religious services weekly. Biden was also the top choice of South Carolina Democrats who care most about nominating a candidate who “can unite the country”: He received 55 percent of their votes.