Washington (CNN) A super PAC promoting Democrat Cory Booker's presidential campaign raised a little more than $1.1 million during the first six months of this year -- falling well short of its fundraising goals as the party's activists and many of its candidates denounce big money in the 2020 election.

Steve Phillips, the San Francisco lawyer and veteran Democratic donor behind the super PAC, Dream United , last year announced plans to raise $10 million to support Booker and said he already had attracted millions of dollars in commitments.

"I remain confident there's going to be $5 million to $10 million for an independent effort for him," Phillips told CNN on Sunday. "This is really a down payment on that. It's just been a little bit slower than initially anticipated."

The biggest donor to the super PAC: Susan Sandler, Phillips' wife and the heir to a California banking fortune. She donated $1 million to Dream United, according to a statement provided first to CNN. Other donors: Boykin Curry , a partner in the investment firm Eagle Capital, who donated $100,000 and $25,000 from New York lawyer Eunu Chun

Booker, like most of his rivals for the 2020 Democratic presidential nomination , has declared that he does not want help from super PACs. Super PACs can raise and spend unlimited amounts as long as they do not coordinate their spending decisions with candidates. By contrast, an individual cannot donate more than $2,800 to a candidate for the primary or general election.

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