Environmental groups are going to fight like hell against Republicans in the 2016 presidential election, but they have no intention of going easy on Hillary Clinton either.

As Clinton prepares to announce her campaign—a formal announcement is expected Sunday—environmental groups are preparing a series of stress tests for the Democratic front-runner, hoping to get assurances that she’ll hold their line on a host of green issues.

Climate-activist group 350 Action will hold a demonstration on Monday outside Clinton’s New York headquarters, where protesters will call on Clinton to clarify her stand on the Keystone XL oil-sands pipeline. And following the announcement, 350 Action, the Center for Biological Diversity, and other groups plan to push Clinton to take stands on other issues, including fracking and other federal financial supports for the fossil fuel industry. (The effort kicked off on Friday when more than 100 groups, including environmental-advocacy organizations such as Friends of the Earth and the Center for Biological Diversity, penned a letter to Clinton calling on her to oppose fracking.)

The groups want firm, on-the-record commitments from Clinton, hoping to hold her to green promises later in the campaign and, should she win, as the next president.

So far, they’ve gotten few explicit guarantees. Clinton has famously declined to say what she thinks of Keystone, and in the run-up to her announcement, she has said little about other environmental issues as well. Indeed, Clinton has kept largely quiet on most policy issues, save for the occasional Twitter post or statement. But for environmental groups looking for a Democrat to champion causes they’re sure Republicans won’t, the lack of explicit policy guarantees is worrisome.

“Clinton has got to tell us what she stands for,” said Bill Snape, a senior counsel with the Center for Biological Diversity. “If we’re going to be asked to trust her, then she has to verify where she stands. That’s all we’re asking, and she hasn’t yet delivered.”

The moves are part of a delicate, codependent relationship between the candidate and the environmental movement.

Green groups need Clinton (or any other Democrat) to beat the eventual GOP nominee, lest they find themselves with a president totally at odds with their stances. But they can’t afford to offer unconditional support for fear that the candidate will not prioritize their issues amid the sea of Democratic causes.

Many of the most prominent green groups, including the Sierra Club and the League of Conservation Voters, have been hesitant to criticize Clinton. But grassroots and progressive groups have long expressed concern over a Clinton 2016 run.

“I think she has a lot of ground to make up if she’s going to get enthusiastic support from the environmental world,” Bill McKibben, the founder of grassroots environmental group 350.org, said in an interview.

For Clinton, the reluctance to delve into details when it comes to the environment reflects careful political calculation. She wants to galvanize the key constituency, but—like any primary candidate—she wants to avoid taking positions that could hurt her among independents in the general election. Taking a stand on an issue like Keystone, which has become a purity test for environmentalists but is a cause of controversy among the general public, is a fraught proposition.

So where does the former secretary of State stand on green issues?

For one, she has called climate change “the most consequential, urgent, sweeping collection of challenges we face as a nation and a world.” And her Senate voting record reflects support for green causes.

The League of Conservation Voters has praised Clinton for calling for action on climate change and applauded her overall environmental record. “As secretary of State and New York senator, Clinton had a strong record of leadership in support of public health safeguards and climate-pollution reductions,” said Daniel J. Weiss, LCV’s senior vice president for campaigns. “Everything about her past record and recent speeches suggest that she will continue to do so.”

Clinton has already earned endorsements from Senate climate advocates Barbara Boxer, Brian Schatz, and Sheldon Whitehouse.

But Clinton has also been accused of cozy ties with the oil and gas industry, and she has come under fire from climate activists amid revelations that the Clinton Foundation accepted millions of dollars from major oil and gas companies and a Canadian agency promoting construction of Keystone. The former secretary of State has also expressed cautious support for fracking, a controversial drilling technique that many environmental groups staunchly oppose.

And some of the groups who operate further from the Democratic Party’s center are more tepid on Clinton, part of a broader grassroots skepticism about the primary front-runner’s progressive credentials.

350 Action and Friends of the Earth, in particular, have long urged Clinton to take a stand on Keystone. “She will soon be a declared presidential candidate, and she owes the American people an explanation of what her thinking is on this,” said Karthik Ganapathy, a spokesman for 350 Action.