“Many have not been involved in politics in the past, but they’ve said they can’t sit out this election,” she said.

Ms. Hartley, who hosted an event in recent months to pitch donors on the idea, is one of five organizers of the project, donors said. The others include Robert E. Rubin, the former treasury secretary under President Bill Clinton; Roger C. Altman, the former deputy treasury secretary in the Clinton administration; and two investment bankers who are major Democratic fund-raisers, Deven J. Parekh and Blair W. Effron.

Ms. Hartley, the only of the five to return calls for comment, declined to discuss how candidates would be chosen, but others briefed on the group’s plans said they plan to stay mostly away from contested Democratic primaries and the ideological battles that are roiling the party across the country.

Instead, the group is focusing on bolstering Democratic candidates in general election battleground races, with the goal of flipping 24 Republican seats to take the House in November.

Donors who got pitches to contribute said the group was focused on quantitative criteria that included the results in the past election, such as if President Trump or Hillary Clinton carried a district, as well as the ratings of the Cook Political Report and Larry Sabato, a race prognosticator. Candidates have not been brought in for interviews.