“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.