Environmental issues have taken a backseat in this campaign—so far. But a multi-jurisdictional investigation may shift the national focus to the question of corporate culpability for climate change—in particular, whether oil colossus ExxonMobil should be dragged into court.

And that focus could make life a little complicated for Hillary Clinton.

Her family and campaign have ties to ExxonMobil that worry many climate-change activists.

The connections have spurred a steady stream of protests, event-interruptions, and general shin-kicking for the Clinton campaign from activists—and Exxon’s growing legal scrutiny means they’re unlikely to abate.

At issue, as Politico reported on Monday, is whether Exxon executives knowingly suppressed information about fossil fuels’ contribution to climate change—and whether the company should face legal consequences the way tobacco corporations did.

Attorneys general in New York and the U.S. Virgin Islands have subpoenaed corporate communications. The efforts present “the biggest existential threat the company has faced in decades,” Politico wrote.

For Clinton, the timing isn’t exactly ideal. The likely Democratic presidential nominee has long struggled to win the trust of groups and activists calling for more government action on climate change. And that’s in part due to her history of accepting campaign contributions bundled by oil companies’ lobbyists. The Clinton Global Initiative has also taken hefty sums from oil companies (including Exxon), drawing calls for divestment.

But Clinton hasn’t been silent on public policy issues involving Exxon. When an activist with 350.org pressed her on the subject last October—after Bernie Sanders and then-competitor Martin O’Malley took the same position—she voiced support for a Department of Justice investigation of ExxonMobil. But that won’t be enough to quell some environmental activists’ doubts, especially given her family foundation’s openness to Exxon’s largesse.

The company gave the Clinton Global Initiative between $1 million and $5 million, according to Clinton Foundation’s publicly available numbers. Their willingness to take oil money has drawn unstinted criticism from activists, who hold that the foundation legitimizes Exxon and other cohorts by essentially selling them good PR.

“It green-washes them, especially with the trouble that Exxon is having now with all of its past history coming to light—showing that they’ve known about climate change for decades,” said Wenonah Hauter, the executive director of consumer rights group Food & Water Watch, an offshoot of Public Citizen.

“I think if you take a hard look at the Clinton Foundation and how they’ve addressed climate change, I do think it leads to some skepticism about the sincerity of really dealing with these problems,” she added.

The Clinton campaign did not respond to a request for comment.

Hauter and other activists hold that the Clintons and their foundation take too gradual an approach to climate change—and that the fossil fuel money they get makes it hard for activists to trust them.

“I think that the foundation is compromised in its climate work by how much money it has taken from Exxon and other oil companies as well,” said Catherine Thomasson, who heads Physicians for Social Responsibility, the U.S. affiliate of the Nobel prizewinning International Physicians for the Prevention of Nuclear War.

“Everyone should keep these companies at arms’ length,” said Bill McKibben, one of the most influential environmentalists of the past 50 years. “They are, after all, working hard to make sure no government stops them from wrecking the planet.”

Contributing to the foundation isn’t the only way Exxon has financially supported the Clintons. Ursula Burns, a member of the company’s board of directors, gave the maximum contribution of $5,400 to Clinton’s campaign—making Clinton one of a very small number of Democratic candidates to get any financial support from an ExxonMobil board member.

More significantly, in terms of cash, only three Republican presidential candidates got more money from the oil and gas industry as a whole than Clinton did, according to OpenSecrets. And, as Politico noted, the corporation’s senior lobbyist Theresa Fariello is a Clinton bundler. GreenPeace has also dinged Clinton for the fact that at least seven Exxon lobbyists bundle contributions for her campaign.

On the trail, activists have tried to needle Clinton over her connections to oil and gas companies. And sometimes, they’ve successfully gotten under her skin.

“I do not have, I have money from people who work for fossil fuel companies,” Clinton said on March 31, snapping at a protester who challenged her on the issue at a campaign stop.

“I’m so sick—I’m so sick of the Sanders campaign lying about me,” she continued. “I’m sick of it.”

Clinton’s fossil fuel ties have also been a source of disturbance at some of her fundraising events. This month, two activists affiliated with McKibben’s group, 350.org, crashed a Women for Hillary fundraiser with banners that read “Women Against Fossil Fuel Money.”

“Any politician who accepts money from lobbyists of an industry whose business model is predicated on digging up fossil fuels can’t be expected to protect our climate and our communities,” said one participant, Lilly Daigle, in a press release from the group. “There is a new standard for fossil fuel interests in politics: no amount of money is acceptable.”

If that zero-tolerance-for-oil-money argument takes root among a large enough swathe of climate change voters, Clinton may have to win over a whole bunch of Republicans to compensate.