David O'Sullivan and his brother Thomas emigrated to the United States in 1925, settling in New York City.

[4][5] Sullivan allied himself with George Scalise, president of a small BSEIU local of window washers and the international union's representative for the East Coast.

Beginning in 1941, BSEIU President McFetridge attempted to repeatedly "try" Sullivan before various union bodies, but was rebuffed numerous times by state and federal courts.

In part, Sullivan's stronger political position resulted from his union's growing membership: Local 32B now had more than 36,000 members in 5,000 office buildings and 22 department stores.

McFetridge was an advocate of the Marina City mixed-use development in Chicago, which he believed would provide numerous jobs for his members.

McFetridge asked that BSEIU invest pension funds in the development, a plan which Sullivan opposed.

Despite McFetridge's retirement as Local 1 president, he signaled that he wanted to retain his position on the AFL-CIO executive council.

For much of 1965, Sullivan lobbied AFL-CIO president George Meany and other union leaders to dump McFetridge.

A number of younger, more activist leaders whose bases of support lay in these two groups were challenging Sullivan for leadership.

Sullivan retired, and California public sector labor leader George Hardy was elected his successor.