Hillary Clinton easily won the U.S. Democratic presidential primary in South Carolina on Saturday, cementing her status as front-runner in her party's race and delivering a key defeat to Bernie Sanders ahead of the crucial Super Tuesday nominating contests.

Clinton won the backing of almost three-fourths of Democrats who went to the polls in the first Southern state to vote during the presidential candidate nominating season.

The result was never really in doubt. The only question was whether Sanders, a U.S. senator from Vermont, could narrow what was nearly a 30-percentage-point deficit in recent opinion polls.

The Sanders campaign quickly released a statement from the candidate congratulating Clinton on her victory. 

"Tomorrow, this campaign goes national," Clinton told cheering supporters at a primary evening rally here.

Democratic presidential candidate Hillary Clinton
Democratic presidential candidate Hillary Clinton talks to supporters after her victory in the South Carolina Democratic presidential primary in Columbia, Feb. 27, 2016. (W. Gallo/VOA)

Clinton has now won or tied in three of the first four contests in the Democratic nominee selection process and has significant leads in opinion polls in many of the states set to vote next Tuesday.

Speaking to reporters at a Minnesota airport, Sanders said, "In politics on a given night, sometimes you win, sometimes you lose. Tonight we lost.'' Before addressing a rally in Rochester, Minnesota, where voters will decide between the two Tuesday, Sanders spoke of 11 contests in three days: "We intend to win many, many of them.''

The South Carolina victory was notable in that it suggests Clinton’s popularity remains strong among minorities, said Jim Guth, a political science professor at Furman University in Greenville.

“It certainly means she has solidified her pre-existing support, especially among African-Americans, who are a very large part of the primary constituency here,” Guth said.

Sanders looks ahead

Sanders had all but given up on winning South Carolina and focused instead on states voting Tuesday.

"Let me be clear on one thing tonight. This campaign is just beginning. We won a decisive victory in New Hampshire. She won a decisive victory in South Carolina," Sanders said in his written statement Saturday evening. "Now it's on to Super Tuesday."

Nearly a quarter of the Democratic delegates will be up for grabs in the Super Tuesday voting on March 1. Voters in 11 states will pick delegates for each of the two political party nominating conventions, making Tuesday the most important day for Republicans as well as Democrats.

Albert Gates places a sticker on his chest after v
Albert Gates places a sticker on his chest after voting in the South Carolina Democratic primary at a polling place at Sanders Middle School in Columbia, S.C., Feb. 27, 2016.

In her victory speech, Clinton took on front-running Republican Donald Trump, who has said he will make America "great again."

"America has never stopped being great,'' Clinton said, adding that the country needed to be made "whole again."

Speaking earlier Saturday to a large crowd in Austin, Texas, Sanders also spoke of the Republican billionaire businessman.

“We will defeat Trump,” Sanders said. “The American people do not want a president who insults Mexicans, Muslims, women, African-Americans, veterans, and basically anyone who isn’t just like him.”

Sanders, who draws the bulk of his support from younger voters and whites, now faces an uphill battle, after losing two consecutive states to Clinton.

“He has to do more than break even when it comes to winning delegates from this point on, and that seems unlikely, especially if he can’t increase the size of his electoral constituency," Guth said.

Low turnout

One bright spot for Sanders was the relatively small number of voters who showed up at polling places Saturday in South Carolina, raising the question of whether Clinton can energize her core supporters.

One of those voters was Columbia resident Evelyn Boyd, who cast a ballot for Clinton.

“She stands up for the rights of the people. She is not afraid of the foreign governments, because she has worked with them,” Boyd said.

Edward Suhy, a waiter and bartender who lives in Columbia, supported Sanders.

“He seems to actually care about people, and I think he has got a really good heart. I am just sick of the status quo every single year,” Suhy said.

Former U.S. President Bill Clinton campaigns for h
Former U.S. President Bill Clinton campaigns for his wife, Democratic presidential candidate Hillary Clinton, as she rallies with supporters at an outdoor plaza in Columbia, South Carolina, Feb. 26, 2016.

Despite the low turnout, Clinton’s campaign has reason to be optimistic, according to David Woodard, who teaches political science at Clemson University.

“I think most everybody will forget all that when she finally has a big win like this in a Southern state,” Woodard said. “I think that all adds up for her.”

Woodard, who is also a Republican political consultant, said Clinton would like to soon focus on her likely Republican opponent in the general election.

“I think she’d rather face Trump, and I think she might,” said Woodard. “I think [Florida Senator Marco] Rubio is a more formidable opponent, but I also think he has a harder way to get there.”

U.S. Democratic presidential candidate Bernie Sand
U.S. Democratic presidential candidate Bernie Sanders and his wife, Jane, listen as Guy Forsyth performs "This Land Is Your Land" at a campaign rally in Austin, Texas, Feb. 27, 2016.

Republican race intensifies

Rubio and Trump spent Saturday exchanging fierce personal insults, underscoring the extent to which the Republican race has turned into a political street fight.

At a rally in Atlanta, Georgia, Rubio mocked Trump, saying the ex-reality television star has the “worst spray tan in America.”

“Donald Trump likes to sue people. He should sue whoever did that to his face,” Rubio said, drawing laughs from the crowd.

Trump held a rally in Arkansas with Chris Christie, the New Jersey governor who dropped out of the presidential race and endorsed Trump this week.

The New York businessman repeatedly belittled Rubio, saying he has a “fresh mouth” and is a “light little nothing.”

“He’s a very nasty guy,” Trump said of Rubio. “I actually thought [Texas Senator] Ted Cruz was a liar, but Rubio is worse.”

Trump is leading the polls in almost all of the 11 states set to vote Tuesday. A major victory in those states would mean he is all but certain to gather enough delegates to clinch the nomination, although Cruz leads among Republicans in his home state of Texas, the largest prize on Super Tuesday.

WATCH: South Carolina Democrats Discuss Presidential Preferences