Editor’s Note: Since publication of this story, Tom Steyer’s office reached out to The Daily Beast with the following statement: “My wife and I signed the Giving Pledge because we want to leave our kids a different kind of inheritance—an example of at least trying to lead a worthy life. That’s why we’ve committed to giving the vast bulk of our money to charitable pursuits. I have always been clear that my wife and I will fulfill the Giving Pledge to give at least half of our wealth to charity—and that this endeavor is wholly separate from any money I spend in my political efforts. Through my political work, I’ve committed myself to leveling the political playing field and giving our kids a shot at a cleaner, more sustainable future. This is critically important work, but I have always been unequivocal throughout my advocacy that none of the money I spend in those political efforts will be considered—in any way—part of the charitable donations we make and will make as part of the Giving Pledge.”

Five years ago, 40 of the country’s richest billionaires came together and publicly proclaimed that they would give at least half of their fortunes to charity before they died. Called “the Giving Pledge,” the idea was to generate publicity to peer-pressure fellow fat cats into giving away most of their wealth, too.

Since 2010, the Giving Pledge has grown to more than 100 signers, and gone global. And now, in an era of SuperPACs and metastasized campaign spending, the Giving Pledge could go political.

In April, Chris Lehane, a top aide to Tom Steyer, a hedge-fund manager turned environmental crusader who poured $74 million into the 2014 election to elect environmentally-friendly Democrats, was asked by reporters how much Steyer planned to spend in 2016. Lehane declined to state a figure, but did remind the press that Steyer had signed the Giving Pledge.

Lehane added that so long as political advocacy spending would not advantage the giver economically, it was within the spirit of the pledge.

“In a democracy, influencing public policy to help improve the lives of the next generation often means getting involved in politics. That is how Tom sees it,” Lehane said, pointing out that Steyer also is involved in several non-political ventures, including Too Small to Fail, an initiative that is a combined effort of Steyer’s Center for the Next Generation and the Bill, Hillary and Chelsea Clinton Foundation.

In Hillary Clinton’s last public appearance before jumping into the race for president, she appeared in Brooklyn on behalf of Too Small to Fail, and sat next to Steyer at a League of Conservation Voters dinner in New York. And even though Clinton has not said where she stands on the construction of the Keystone XL oil pipeline—the killing of which has been one of Steyer’s pet causes—the hedge-fund manager is slated to host Clinton in his northern California home next week.

The promises of the Giving Pledge are voluntary and nonbinding, meant to symbolize a commitment to charitable causes. An official with the group said each person who pledges must make an individual decision about which particular causes or organizations to support.

Asked whether a donor can fulfill his or her Giving Pledge commitment by contributing to political advocacy, a spokesperson replied in a statement: “The Giving Pledge is an effort to help address society’s most pressing problems by inviting the world’s wealthiest individuals and families to commit to giving more than half of their wealth to philanthropy or charitable causes either during their lifetime or in their will,” and pointed to the Frequently Asked Questions page of the group’s website.

That page, however, does not address political advocacy either. The Daily Beast spoke to advisers of three billionaires and Giving Pledge signers, and all said their understanding was that the pledge was meant to include charitable work, and not political giving or political advocacy.

Steyer has been a frequent antagonist of Charles Koch and David Koch, the energy magnates who are the fourth- and fifth-richest people in America, challenging them publicly to a debate and accusing the brothers of benefiting financially from their political giving by making “donations that line up perfectly with their pocketbooks—that is not true for us.”

The Koch brothers had not taken the Giving Pledge, and Lehane’s definition of what makes political giving part of the pledge—that it not benefit the donor financially—would exclude the pair, who give millions to Republicans who call for lesser governmental regulations.

A Koch spokesperson declined to comment, but conservatives frequently have accused Steyer of benefiting financially from his political push toward renewable energy.

As the Giving Pledge has grown, it has come under some criticism for being little more than a PR ploy for some of the world’s richest people and for not ensuring that the donations go to the worthiest causes. In 2014, the Chronicle of Philanthropy reported that nine of the top 50 givers on the list had written their biggest checks to their own family charities, which can be seen as vanity projects with poor oversight.

As Lehane mentioned, the line between what is political and what is not can often be blurred. If a wealthy donor cared about reducing poverty, for example, it would follow that he or she would not only try to elect candidates who pledged to do that, but also give to organizations that took up the cause and publicly made their case through issue-based advertisements.

Aaron Dorfman, executive director of the National Committee for Responsive Philanthropy, said the pledge was meant to include direct service, research, universities, and advocacy, and that PACs and political spending “don’t strike me as something commensurate with the pledge.”

Political spending, he added, “is an important part of making a difference in the world. There is a space for political giving and it’s important to note that there are a whole range of ways to influence the world, and it’s a smart strategy. But if you say that political giving is part of your pledge to give away half of your wealth, well, I am not sure that counts.”

Surely, if more participants of the Giving Pledge steered more of their money toward political giving as part of fulfilling their pledge, it would mean even more money in the political system. The 120-plus signers of the Giving Pledge have a combined estimated worth of more than $600 billion.

“You can believe that it is a charitable thing if you are the person with the money, but I think for most people it would be like an attempt to buy action on your point of view,” said Dale Eisman, a spokesman for Common Cause.

Feel free to advocate for your chosen cause, he added, even if that cause is political in nature. “Just don’t call it philanthropy.”