“The attacks aimed at this campaign from dark money groups helping Donald Trump spread his outlandish lies and slander have only served as a reminder of the urgent need for campaign finance reform,” Mr. Ducklo said. “Which is exactly why since the beginning of this campaign, Biden for President has not and will not welcome the help of super PACs. That goes for those that purport to help him, despite his explicit condemnation of their existence.”

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In addition to its public statements, Mr. Biden’s campaign has warned off some Democrats from participating in a super PAC. One prominent Democrat, David Wilhelm, a former chairman of the Democratic National Committee, said he had been approached about being involved in the pro-Biden super PAC but had declined to do so after the campaign urged him against it.

Mr. Riddle said a final decision about whether to deploy a super PAC for Mr. Biden would be made in “the coming weeks.”

Mr. Biden clearly needs to jolt his campaign, which has lost ground in the early nominating states to Senator Elizabeth Warren, who has been largely unscathed by her rivals. And the vice president’s longtime friends increasingly believe that Ms. Warren’s growing strength — along with Mr. Trump’s offensive — is reason enough to risk the backlash they would get from their opponents and campaign finance reform advocates for creating a group reliant on large contributions. But Mr. Riddle said there had been no final decision on whether to proceed with a super PAC, in part because of this risk. Mr. Biden’s two leading competitors for his party’s nomination, Ms. Warren and Senator Bernie Sanders of Vermont, have made getting big money out of politics a major theme of their campaigns. And Mr. Biden has already drawn criticism for his comparative reliance on wealthy donors to fund his candidacy.

“I’m mindful that any effort to do this is going to be disowned by the campaign because of the way Warren has replayed her hand,” said Mr. Rasky, alluding to the senator’s decision not to solicit large campaign checks as a presidential candidate, despite having done so in her Senate campaign.

Mr. Riddle said that any pro-Biden advertising would be focused on responding to attacks from Mr. Trump and Republicans, rather than targeting other Democrats.

Despite Mr. Munger’s presence at the meeting last week, Mr. Riddle said Mr. Munger was not involved in devising the pro-Biden group and had not contributed any money so far. Mr. Munger is the son of Charles Munger, a billionaire who is the vice chairman of Berkshire Hathaway, Warren Buffett’s investment firm.