Gov. Kate Brown’s re-election campaign is the largest donor to a group called Defend Oregon’s Values, which is running TV ads attacking Republican challenger Knute Buehler.

Defend Oregon’s Values reported receiving $100,000 from Brown’s campaign, according to a disclosure record newly filed with the Oregon Elections Division. Political committees connected to the Oregon Education Association and frequent democratic donor Eric Lemelson also each reported giving $50,000 to the advertising effort.

The money behind Defend Oregon’s Values came into focus during a period when most of the advertising in the governor’s race is not actually being run by the Buehler and Brown campaigns.

One of the biggest TV presences in the race is Priority Oregon, a non-profit that has provided few details about its funding. The group has run a series of ads attacking the Democratic governor, including one recent commercial charging she’s responsible for a failing mental health system in the state.

Oregon doesn’t have any limits on how much donors can give to candidates. But Defend Oregon’s Values can run attack advertising without the casual voter being aware that Brown’s campaign is helping fund the effort.

In addition, Priority Oregon can run its ads without having to disclose how they are funded. The group is allowed to do so because it’s organized as a charitable organization that runs ads that don’t explicitly advocate support or opposition to any candidate.

The group is supposed to file yearly reports with the IRS that include information about its board and its overall finances. But it got an extension that could push back its report until after the November general election.

“[W]e filed an extension, which is not unusual,” Erica Hetfeld, Priority Oregon’s executive director, said in a text. “At that time, all the information that we’re required to disclose will be public record.”

Christian Gaston, Brown’s campaign spokesman, said Defend Oregon’s Values was set up by a coalition seeking “to respond quickly to Priority Oregon’s misleading ads.”

Besides Brown, the two main contributors to Defend Oregon’s Values revealed so far are mainstays of democratic campaigns. The Oregon Education Association is the state’s largest teacher’s union. Lemelson is a philanthropist and winemaker from Dayton who is the primary funder of the Oregon Climate PAC.

Gaston said there was no intention to distance Brown from advertising criticizing Buehler, a physician and state representative from Bend. The groups ads attacked Buehler for his votes on health care and abortion.

Buehler spokeswoman Monica Wroblewski said that “our organization has absolutely nothing to do with Priority Oregon.”

In addition to running ads attacking Brown, Priority Oregon has also been involved in several initiative campaigns that received donations from a variety of business groups. It played a key role in drafting Measure 104 on the November ballot. The initiative would require a three-fifths legislative majority for all tax and fee increases.