Businessman Jeffrey Katzenberg and media proprietor Haim Saban are also said to have given $1 million each. Other donors to the group, an independent expenditure committee that can collect unlimited contributions from donors, included filmmaker J.J. Abrams and his wife and actress Katie McGrath, who gave $500,000 each, reports variety.com.
Saban's wife Cheryl also gave $1 million. The group reported raised $15.7 million in the first six months of the year.
The deadline for the political action committees to file mid-year disclosure reports with the Federal Election Commission was July 31.
Katzenberg has been helping Priorities USA Action raise money from high-dollar donors this cycle. He was a founding donor and fundraiser for Priorities USA Action when it was initially set up to support president Barack Obama's re-election bid in 2012.
Other prominent donors to the group included investor George Soros, who gave $1 million, and Los Angeles-based investor Marc Nathanson, who gave $250,000.
Founded in 2012, Priorities USA Action aims to communicate a progressive vision that increases economic security and upward mobility for middle class families.