Conservative nonprofit groups that have advocated for the natural gas industry funded hundreds of thousands of dollars worth of attack ads in last month’s primary election in two state House races in the Philadelphia suburbs.

Outside political groups spent at least $517,000 on Democratic primary races in Chester County, according to newly disclosed campaign records and data compiled by the ad tracking firm Advertising Analytics.

The targets of the attack ads were first-term state Rep. Danielle Friel Otten and Ginny Kerslake, both Democrats and outspoken opponents of Sunoco’s Mariner East pipeline project, which carries natural gas liquids from the Marcellus and Utica shale formations to the company’s terminal in Marcus Hook.

Otten won her primary. Kerslake lost to incumbent Democratic Rep. Kristine Howard.

That much spending in state House races is unusual — and it came so late in the campaign that one of the political groups involved didn’t have to disclose its donors until a month after the June 2 election.

Tracing the funding is almost impossible, as the nonprofits behind it are not required to disclose donors. The spending underscores the influence of “dark money” in seemingly low-profile races, as well as the stakes associated with the controversial pipeline project, a political and legal flash-point in the debate over energy and the environment.

“It just was insanity to me that one legislator can be that powerful that they would spend a quarter of a million dollars to try to take me out in the primary,” Otten said in an interview.

She said she suspected the oil and gas industry was involved and wanted to “make an example of me, because I have been very outspoken about the egregiousness of what that industry is doing.”

Environmental groups have spent big on local elections, too: Conservation Voters of Pennsylvania pumped $250,000 into Chester County races last year, helping Democrats win control of the county commissioners’ board for the first time. One of the group’s biggest donors was the Washington, D.C.-based League of Conservation Voters Inc., a nonprofit that does not have to disclose its donors.

Pennsylvania’s 167th House District was one of 14 seats Democrats flipped in 2018 as the GOP fell out of favor with suburban voters nationally in President Donald Trump’s first midterm election. Howard defeated the Republican incumbent by four percentage points, or fewer than 2,000 votes.

Kerslake had managed Otten’s successful 2018 campaign against a GOP incumbent and decided to challenge Howard this year in the primary. “It’s really important we have someone who’s going to be our ally and stand up for us,” said Kerslake, founder of Del-Chesco United for Pipeline Safety.

A group called Stronger Pennsylvania PAC, chaired by veteran Pittsburgh-based Democratic strategist Mike Mikus, registered with the IRS on May 8. By the end of the month, it was on the airwaves declaring Kerslake had been “bankrolled by out of state special interests” and “dirty money” — accusations Kerslake said were false.

Stronger Pennsylvania’s budget was funded almost entirely by a $200,000 check it received five days before the election from a Virginia-based organization called Frontiers of Freedom Foundation.

Founded in 1995 by Malcolm Wallop, a Republican U.S. senator from Wyoming, Frontiers of Freedom describes itself as a public policy think tank “devoted to promoting a strong national defense, free markets, individual liberty, and constitutionally limited government.”

In the early 2000s, the foundation received hundreds of thousands of dollars from ExxonMobil, the New York Times reported at the time. The foundation hasn’t filed the required tax forms with the IRS since 2007, when it reported just $2,000 in revenue and $20,411 in net assets. The IRS revoked Frontiers of Freedom Foundation’s tax-exempt status in 2010, records show.

But the organization’s leadership started a political action committee, Frontiers of Freedom Action Inc., in 2017. In its most recent government filing the group reported about $47,000 in contributions from small donors this spring. It said nothing about Stronger Pennsylvania.

Records filed in Virginia show Frontiers of Freedom is registered as a nonprofit.

It wasn’t clear which entity associated with Frontiers of Freedom made the contribution. The organization’s president, George Landrith, didn’t respond to requests for comment. Stronger Pennsylvania’s chairman, Mikus, also didn’t have an explanation.

On its website, the group promotes a 2019 “Ronald Reagan gala” it hosted at the Trump International Hotel down the street from the White House to honor U.S. Sen. Rand Paul (R., Ky.). A table for 10 went for as much as $15,000.

In January, Landrith wrote opinion articles in local newspapers in Chester and Delaware Counties that criticized the Chester County district attorney for bringing charges against security contractors who were hired to protect the Mariner East pipeline.

“Sadly, the accusations are merely another publicity stunt in the DA’s crusade to upend the permitted project rather than an honest effort to serve the public,” Landrith wrote.

Howard, the incumbent, spent $69,000, while Kerslake spent $27,000 over the campaign. The two candidates’ spending was dwarfed by the nearly $200,000 spent by Stronger Pennsylvania, which in addition to attacking Kerslake praised Howard as a pro-environment candidate.

Howard said she did not know anything about the group, which as an independent expenditure committee is prohibited from coordinating with campaigns. She also said she wasn’t a big fan of outside spending. “When you don’t know who they are and they aren’t really promoting your message, I think it is something that needs to be tightened up,” she said.

She also said most voters had already cast their mail ballots by the time the PAC hit the airwaves. “They came out with those cheesy commercials,” Howard said. “It was like the last weekend. I just thought, you know what, they’re spending so much money and it’s too late, really.”

Howard won with 59% of the vote and faces Republican Wendy Graham Leland in the general election.

In Pennsylvania’s 155th House District, a political action committee called Building for America’s Future, which was created in October, bought commercials attacking Otten in the final weeks of the campaign. The PAC spent a total of almost $324,000.

By contrast, Otten and her challenger, Rose Danese, each spent about $17,000.

As with Stronger Pennsylvania, Building for America’s Future’s budget was bankrolled by a single entity: Consumer Action for a Strong Economy (CASE), an Arlington, Va.-based conservative nonprofit that cut two checks in May totaling $356,750.

A spokesperson for Building for America’s Future said the PAC “complies with all state campaign finance laws and filing requirements.”

CASE says it serves as “the voice of American consumers and wage-earners by advocating strongly for free-markets, fiscal responsibility and reasonable consumer protections.”

The organization registered with the IRS in 2017 as a tax-exempt “social welfare” group. Such groups are permitted to make political contributions, as long as such giving does not account for the majority of their spending. They are not required to disclose their donors.

One glimpse into the group’s finances came from tax filings made by one of its donors, Pharmaceutical Research and Manufacturers of America. The trade group contributed $170,000 in 2018 to Consumer Action for a Strong Economy, according to a tax filing and reporting by the Center for Responsive Politics.

CASE reported $1.3 million in revenues in 2018, the most recent year for which records were available. The organization didn’t respond to a request for comment.

Consumer Action for a Strong Economy has supported the natural gas industry. In a 2019 opinion article for the Scranton Times-Tribune, CASE president Matthew Kandrach wrote that Democratic Gov. Tom Wolf’s proposal for a severance tax on drillers would “haunt the state for years to come” and “expose Pennsylvania to the risk of a loss of revenue and jobs.”

“Jacking up taxes on gas production to pay for planned infrastructure improvements is a misguided attempt to deal with the state’s chronic problems in the short term that would cost billions in the long term,” he wrote.

Building for America’s Future’s commercials attacked Otten as an ineffective lawmaker who “wastes taxpayer funds” and is “in it for herself — not for you.”

The ads didn’t appear to have much of an impact: Otten defeated her primary challenger with 74% of the vote.