Steve Phillips, a San Francisco lawyer and founder of Dream United, indicated in a news release that the super PAC had struggled to raise money. Booker, D-N.J., has publicly disavowed support from super PACs, which aren't required to disclose their donors publicly.
"We remain firm in our belief that Senator Cory Booker is uniquely qualified to unite and heal Americans across this country at this critical point in our history," a statement on Dream United's website read. "Respecting the Senator’s publicly-stated sentiments about SuperPACs, Dream United will cease operations effective immediately."
Phillips, a Stanford University classmate of Booker, said in his statement that it became clear while trying to fundraise "that the donor community is strictly adhering to Senator Booker’s publicly articulated wishes that he does not welcome independent support."
The group raised a little over $1.1 million during the first six months of the year, far short of Phillips' stated goal of $10 million. Politico reported in July that almost all of those funds were contributed by Phillips' wife, Susan Sandler. The couple have previously helped raise money for high-profile black candidates, including former President Barack Obama and Sen. Kamala Harris, D-Calif.
Booker's campaign has struggled to gain traction. A Fox News poll of Democratic primary voters nationwide published earlier this month showed Booker with 2 percent support, 29 percentage points behind front-runner Joe Biden.
The Associated Press contributed to this report.