The Lincoln Project, the super PAC that has produced a steady stream of ads that slam President Donald Trump, saw its fundraising soar to more than $16.8 million during the second quarter, a new filing shows.

Its single largest donor in the April-to-June fundraising quarter: Connecticut-based hedge fund manager Stephen Mandel, who donated $1 million to the group. Mandel is a Democratic donor who has supported Democratic presumptive nominee Joe Biden’s presidential bid, Federal Election Commission filings show.

Mandel did not immediately respond to an interview request.

Another billionaire Democrat, Hollywood film magnate David Geffen, is among the donors who contributed $100,000. Josh Bekenstein, co-chairman of private-investment firm Bain Capital, also donated $100,000.