“Once you are the Democratic nominee, you are the party,” said Rufus Gifford, a former finance director for President Barack Obama, who has donated to multiple 2020 candidates but not to Ms. Warren. “You own the party. Your political operation takes over the D.N.C. You cannot divorce in any way fund-raising for the presidential campaign and the Democratic Party.”

The donation limits for the D.N.C. are actually far higher than those for direct contributions to campaigns. The D.N.C. can raise money in increments of $355,000; direct donations to a potential Warren general election committee would be limited to $2,800.

Ms. Orthman said Ms. Warren would attend D.N.C. events that are open to the press to “make sure the Democratic National Committee, state and local parties, and Democratic candidates everywhere have the resources” they need. She also said Ms. Warren was “not going to change a thing in how she runs her campaign,” including “no special access or call time with rich donors or big-dollar fund-raisers.”

Ms. Warren headlined a D.N.C. event in August, but she did not meet privately with large donors who attended. She is scheduled for another D.N.C. event next week.

Sign up for On Politics to get the latest election and politics news and insights. Sign up for our politics newsletter

The Warren campaign declined to say whether it would create a joint fund-raising committee with the D.N.C., which is traditionally a big lure for contributors who want to support candidates up and down the ballot. Mr. Trump and his shared committees with the Republican National Committee raised $125 million in the last three months.

Henry R. Munoz III, who stepped down as finance chair of the D.N.C. earlier this year and has co-hosted a fund-raiser for former Vice President Joseph R. Biden Jr., said Ms. Warren’s proposed arrangement left him confused.

“I don’t even know how that would work,” Mr. Munoz said. Democrats, he added, “have to do everything in their power to work together to create an infrastructure to do battle with the almost unlimited resources that this administration and that party will use to destroy what we believe in.”