This is a pretty genius move by Zephyr Teachout.
First, some background, via the Huffington Post:
In May, billionaire Paul Singer fundamentally changed one of the most interesting political contests of 2016. The vulture fund manager wrote a $500,000 check to a super PAC supporting John Faso, a Republican trying to fill an open congressional seat in New York’s Hudson Valley. Overnight, Faso became a serious contender in a race that had been dominated by progressive Democrat Zephyr Teachout.
Faso had been relying on super PAC funding from another hedge fund billionaire, Robert Mercer, to get through a much tighter primary contest on the Republican side. When Singer signed on in May, Faso had the firepower to challenge Teachout in the general election.
On Monday, Teachout decided to bypass Faso himself and go after his donor. In a video posted to her Facebook account, she criticized Singer and challenged him to a debate.