CHARLESTON, S.C. — A top adviser said Bernie Sanders would reject an offer from Mike Bloomberg to spend heavily on his behalf in the general election if Sanders wins the Democratic presidential nomination.

Bloomberg, the billionaire former mayor of New York who is running against Sanders, an independent senator from Vermont, in the Democratic primary campaign, has said he would keep his money flowing to help oust President Donald Trump, regardless of whom Democrats nominate.

But Jeff Weaver, Sanders' closest aide, said the Democratic front-runner would not want Bloomberg's help.

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"It's a hard no," Weaver told NBC News after Tuesday night's debate. "Bernie has said he's going to fund his presidential campaign with small-dollar contributions, and I think we can do that. I think we can raise over a billion dollars in small-dollar contributions."

Sanders cannot control or dictate what independent groups do on his behalf since campaign finance law prohibits candidates from coordinating strategy with outside groups. But Bloomberg's team has said the mogul would not spend on behalf of a candidate who rejected his help.

"Bernie said he didn't want [Bloomberg's] money, so we're not going to. I don't think it would be prudent to spend on behalf of somebody who didn't want it," Howard Wolfson, a senior adviser to Bloomberg, told NBC News after the debate.

"I think everyone else has said they want the help, including Elizabeth Warren," Wolfson added. "If Elizabeth Warren is the nominee, we will do everything we can to help her. Sanders is the one candidate who said he didn't want the help."

Bloomberg has spent more than $500 million on his campaign so far and has said he would keep part of his massive campaign team up and running, along with the TV ads, through November to help Democrats in the general election, whether or not he's at the top of the ticket.

Experts say the unprecedented money Bloomberg seems prepared to spend has the potential to tip the election against Trump, although no one really knows, because no one has tried to spend the kind of money Bloomberg could.

Sanders, however, rails against billionaires who influence politics and has repeatedly accused Bloomberg of trying to buy the White House.

At a rally in North Carolina this month, Sanders said, "We believe in old-fashioned democracy: one person, one vote, not billionaires buying elections."