The former presidential candidate for the Green Party also said she isn't 'unshakably opposed to' a 2020 run.
The adverts are now being looked into as a potential part of the overall Russia probe.
Recount continues in Wisconsin while Michigan's may start this week; Stein to rally at Trump Tower Monday.
Democrat's campaign counsel says there's an obligation to support the effort, which Trump derides as a 'scam,' despite failing to uncover any electoral abnormalities.
Former presidential candidate says she's concerned about the integrity of the vote in the swing state.