Soros also gave another $500,000 to two congressional super PACs, House Majority PAC and Majority PAC.
Soros' contribution to the super PAC Priorities USA Action comes as the group raised a record $10 million last month. It has launched television ads highly critical of Republican challenger Mitt Romney.
Priorities USA Action and the congressional PACs confirmed the amounts of the donations on Thursday.
Soros gave $1 million earlier this year to the pro-Democratic super PAC American Bridge 21st Century. He's contributed millions of dollars during previous presidential elections.
Soros' contribution may signal that Democratic-leaning donors of elections past are starting to come around to super PACs. Those organizations can raise and spend unlimited sums of cash but can't coordinate with the candidates.
Soros' contribution was announced at a fundraising luncheon in New York Thursday. "The gathering, which was headlined by former President Bill Clinton, suggested a rapprochement of sorts between progressive donors who have traditionally favored what they call “movement-building” and Democratic strategists who badly want large checks to pay for the party’s emerging super PAC apparatus," reported The New York Times.
Soros was opposed to pumping funds into super PACs, but according to Mother Jones, he a few months ago changed his mind because he was concerned that Mitt Romney would win the 2012 presidential election. A friend of Soros told Mother Jones:
"He was the last person I ever expected to hear from, given how antithetical he was to the big money slopping around the system. But he said that he was panicked about the fact that Romney could win this."
Copyright 2012 The Associated Press.