In a head-turning memo Sunday, Sen. Elizabeth Warren's campaign declared that "the reality of this race" is that "no candidate will likely have a path to the majority of delegates" at the July Democratic National Convention in Milwaukee, Wis. -- setting out in stark terms the possibility of a bruising convention that party leaders have long feared, and outlining Warren's strategy for winning the presidential nomination there in a dramatic "final play."

The memo came a day after former Vice President Joe Biden scored a strong win in South Carolina's Saturday primary, telling "Fox News Sunday" that his campaign was a "real comeback" story. The win suddenly made Biden the overall popular vote leader in the primary cycle to date by more than 30,000 votes, even as he narrowly trails front-runner Sen. Bernie Sanders in delegates by 8.

Warren, who has turned in disappointing finishes in every primary or caucus to date, could suffer even more losses when 14 states vote on Super Tuesday, including in her home state of Massachussetts. Nevertheless, Warren campaign manager Roger Lau vowed, in the memo, that the campaign won't give up -- and he projected the campaign will receive delegates in "nearly every state in play on Super Tuesday."

Then, the campaign chief said, "all of our 400 Super Tuesday organizing staffers will be re-deployed to states voting in March or April."

"After Wisconsin, nearly one-third of the pledged delegates will still be waiting to be elected, and there will be a three-week gap between electing delegates for the first time since voting began," Lau wrote. "In the road to the nomination, the Wisconsin primary is halftime, and the convention in Milwaukee is the final play."

Lau added: "Our grassroots campaign is built to compete in every state and territory and ultimately prevail at the national convention in Milwaukee."

He noted that the campaign had raised more than $29 million in February, beating expectations.

WATCH: BIDEN SITS DOWN WITH 'FOX NEWS SUNDAY' AFTER MAJOR SC WIN

Under new rules adopted by the Democratic National Committee (DNC) for this election cycle, if no candidiate receives a majority of delegates at the first balloting, then a second ballot will be held in which approximately 700 so-called "superdelegates," or party insiders, would have a say. In 2016, such superdelegates were allowed to vote in the first ballot, rankling Sanders supporters.

"The Wisconsin primary is halftime, and the convention in Milwaukee is the final play."
— Warren campaign manager Roger Lau

Some left-of-center commentators were incensed: "Warren campaign admits that their goal is to steal the nomination from Bernie through corrupt deals at the convention," wrote journalist Michael Tracey. However, Warren and her supporters noted that in 2016, Sanders had suggested that a mere plurality of pledged delegates should not necessarily guarantee the nomination.

"That was Bernie's position in 2016, that it should not got to the person who had a plurality," Warren said at a recent CNN town hall. "So, and remember, his last play was to superdelegates. So, the way I see this is you write the rules before you know where everybody stands, and then you stick with those rules."

Meanwhile, pressure is mounting for lagging candidates to step aside so Biden can engage in a more direct match-up against Sanders, who heads into the coming week eager to surpass his rivals in amassing delegates for the nomination. There were few signs that anyone was leaving the race, though, which would potentially allow some delegates to switch sides and vote for someone else at the convention.

Billionaire Mike Bloomberg, who will be on the ballot for the first time next week, said Sunday he’s not going anywhere before Tuesday’s primaries.

“I’m optimistic," he told voters in Selma, Ala., where many of the White House hopefuls gathered for ceremonies commemorating civil rights heroism. He has spent more than $500 million advertising in the Super Tuesday states.

One dimming rival, Pete Buttigieg, said only that his campaign will be “assessing at every turn” the best steps for defeating Trump. “Our country can’t take four more years of this,” he said on NBC's “Meet the Press.”

Biden, for his part, declined to ask rivals to bow out. “It’s not for me to tell another candidate to get out of the race,” Biden said on "Fox News Sunday.”

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Leveling his own direct attack on Sanders, Biden declared, “The people aren't looking for revolution. They're looking for results.”

Fox News' Adam Shaw and The Associated Press contributed to this report.