Jurvetson and Women.Vote did not respond to requests for comment. Women.Vote did not appear to purchase any Facebook ads, according to Facebook’s ad archive. It’s unclear whether the group has run other ads in other newspapers.

The Warren campaign said it did not know about the ad and asked for the people behind it to stop. Spokesperson Chris Hayden said that the “campaign was not aware of this and asks that those involved immediately stop purchasing advertisements of any kind. Elizabeth Warren believes democracy is undermined by anonymous, dark-money attempts to influence voters — whether that influence is meant to help or hurt her candidacy.”

Warren has sworn off private fundraisers during her presidential campaign and has used that pledge to try to reinforce her central campaign theme of fighting Washington corruption and the influence of money. Faced with financial challenges, other candidates including former Vice President Joe Biden and former Massachusetts Governor Deval Patrick have signaled they would not oppose an outside Super PAC group helping their candidacies.

“501c4s like Women.Vote are often referred to as dark money groups because they are used to influence elections while keeping wealthy donors hidden from the public,” said Brendan Fischer, the director of federal reform at the Campaign Legal Center. “The ad touts Warren’s stated opposition to super PACs, but super PACs at least disclose their donors — dark money 501c4s don’t, so they pose more significant problems.”

Sent the Warren campaign’s statement, Fischer added: “That seems like the right response.”

