Joe Biden Starts General Election Nearly $187 Million Behind Trump

Super PACs — which can accept unlimited donations but are legally barred from strategizing with the campaign itself — will be critical to keeping Mr. Biden competitive in online and television advertising, according to Democratic strategists.

The Biden campaign’s decision last week to single out one super PAC, Priorities USA, above the others in a statement to The Wall Street Journal set off an intense round of rancor that one top fund-raiser likened to a “nuclear bomb” in the political money world. Donors, super PAC strategists and campaign officials have spent much of the last week engaged in shuttle diplomacy to smooth matters over.

Priorities USA, which has existed for the last two presidential cycles, did not support Mr. Biden in the primaries and has some vocal critics among donors who hold the group partly accountable for Mrs. Clinton’s surprise 2016 loss. Among those in Mr. Biden’s orbit who have expressed reservations in the past about Priorities is Steve Ricchetti, a senior Biden adviser and the campaign chairman.

Representative James E. Clyburn of South Carolina, a top Biden endorser and adviser, had worked with a different pro-Biden super PAC, Unite the Country, during the primaries and expressed his displeasure privately as well publicly, saying in an interview that the decision to single out one group was a “mistake.”

“I said before and I’ll say again, I didn’t know who Priorities was,” said Mr. Clyburn, the No. 3 Democrat in the House. “Unite the Country — that’s who I worked with, that’s who I’m still working with.”

As the Biden campaign considered which outside group to endorse, Unite the Country recently added Mr. Clyburn’s daughter, Jennifer Clyburn Reed, as an unpaid board member and announced an alliance with another Democratic super PAC, American Bridge 21st Century, with a goal of raising $175 million.

Those groups were disappointed with the Biden campaign’s initial endorsement of Priorities and, two days later, the campaign put out a second statement that recognized “a community of organizations that have contributions to make” in supporting the candidate. The campaign reissued that same statement for this article, and said its position had never changed and the clarification was only because of misinterpretation.