Doing some digs on ACT BLUE and George Soros and I am finding quite a bit of information and articles. 2 attached links to articles they are older sometimes with information going back to 2008 but you can also start looking at Soros recent contributions and there is a link that can be established.
https://archive.ph/VDtKU
https://www.usatoday.com/story/news/politics/2017/03/20/george-soros-democracy-alliance-anti-trump-activists-meeting/99417808/