(Len Andersson/EPA) (Len Andersson/EPA)

George Soros, the billionaire investor, philanthropist and backer of liberal causes, has signed on to be a co-chair of the national finance council for Ready for Hillary, the super PAC mobilizing support for a possible White House bid by Hillary Rodham Clinton.

“George Soros is delighted to join more than one million Americans in supporting Ready for Hillary,” Michael Vachon, Soros’s political director, said in a statement. “His support for Ready for Hillary is an extension of his long-held belief in the power of grassroots organizing.”