It was hardly Future Forward’s only frustration. Another memo, issued days later, pointed out “very high-performing ads that have yet to get a big spend.” One ad, Future Forward said, had ranked in the “100th percentile” — meaning it was the most effective — yet it had virtually never been aired.

Campaign officials, meanwhile, were frustrated that Future Forward sat on so much of its money until the final weeks, forcing the campaign to spend more on the airwaves earlier.

Another Harris challenge: After raising $1 billion in less than three months, a bevy of consultants, allies and others were often angling for a cut, including the chairman of the Democratic Party in Philadelphia. In September, the Harris operation contributed almost $25 million to other party committees, in part to quiet those demands.

Some media allies of Ms. Harris were also paid. Areva Martin, who hosts a talk show, was paid $200,000 as a media consultant, and she went on a battleground-state tour in October.

Roland Martin, who hosts his own streaming programming and runs a media company called Nu Vision Media, received $350,000 in September for a “media buy” that he said was for advertising.

“It should have been a hell of a lot more,” Mr. Martin said in a brief interview. “More should have been spent on Black-owned media.” Mr. Martin interviewed Ms. Harris in October.

Ms. Harris’s campaign also made two $250,000 donations to National Action Network, the organization led by the Rev. Al Sharpton. Mr. Sharpton interviewed Ms. Harris on MSNBC in October.

As Ms. Harris faced questions about relative weakness among Black voters, her campaign gave $2 million in late September to the National Urban League.

One of the unanswered questions is who exactly made money off the commissions on Ms. Harris’s advertising, which can be especially lucrative. Such payments are often hidden even in federal disclosures.

In 2020, for instance, Mike Donilon, who was one of Mr. Biden’s top strategists, reported on his personal financial disclosure form with the White House that his consultancy had earned $4.35 million in 2020, far more than the roughly $543,000 disclosed to the Federal Election Commission in payments to his firm.

Numerous firms could have netted big commissions from the Harris campaign. Four companies received at least $90 million in payments as of mid-October, including one firm whose cumulative receipts from the Harris campaign approached $300 million.

Shane Goldmacher is a national political correspondent, covering the 2024 campaign and the major developments, trends and forces shaping American politics. He can be reached at [email protected].