Exhortations to citizens to boycott or otherwise cut off the financial funding of those who express unpopular viewpoints or engage in controversial activities have long been a part of the American political landscape.

In early 2017, one prominent instance of this phenomenon has involved the controversial conservative web site Breitbart, which has been targeted by social media campaigns seeking to cut the site’s online advertising revenues, the lifeblood of many digital publishers:

Conservative news website Breitbart News has gotten a lot of attention since Donald Trump was elected, in part because former Breitbart chairman Steve Bannon is now a senior strategist advising the president. But not all of the attention it has received is good.

Over the past month or so, a social media campaign has gradually gathered steam that is aimed at convincing advertisers to stop doing business with Breitbart News. It appears that this campaign is now affecting how even large advertising agencies think about the site, which is known for its ties to racist groups.

According to a leaked memo obtained by BuzzFeed, an Australian agency owned by the global advertising giant Omnicom — which handles advertising and marketing campaigns for all of the major Fortune 500 brands including McDonalds and Apple — has advised its staff that many of the firm’s clients are asking that their ads not appear on Breitbart.

The memo mentions the crowdsourced anti-Breitbart campaign known as “Sleeping Giants,” which encourages Twitter users and those on other social networks to shame large companies into not doing business with Breitbart. The latest update says that over 1,000 advertisers have blocked the site from their media-buying programs.

Of particular note in the online world in March 2017 were petitions urging retailing giant Amazon.com to stop “supporting” Breitbart through advertising:

Breitbart.com is notorious for its racist, misogynistic, hateful propaganda hiding under a thin veil of a ‘news’ site. One of many examples of the misogyny was exposed in a 2011 radio interview when Stephen Bannon (a Breitbart executive and current president-elect’s chief strategist/senior counselor) made the following statement: “…That’s why there are some unintended consequences of the women’s liberation movement. That, in fact, the women that would lead this country would be pro-family, they would have husbands, they would love their children. They wouldn’t be a bunch of dykes that came from the Seven Sisters schools up in New England. That drives the left insane, and that’s why they hate these women…

Kellogg’s has pulled their advertisement from Breitbart.com because the site “does not align with their values.” It is hope that Amazon will be willing to make the same stand that Kellogg’s and other advertisers have taken, turning away from a website that incites divisiveness and hate for no other purpose than to line their own pockets.

As BuzzFeed reported in early February 2017, efforts — unsuccessful so far — to sever ad ties between Amazon and Breitbart were coming not just from the public in general, but from within Amazon’s workforce itself:

As Amazon positions itself as an outspoken critic of President Donald Trump’s immigration policies, inside the company, dozens of employees are voicing deep concern about another political issue: Amazon’s choice to advertise on Breitbart.com.

According to internal emails and documents obtained by BuzzFeed News, employees have begun voicing concerns about the company’s advertising relationship with the provocative far-right website. Some piled on to a complaint ticket in Amazon’s internal issue escalation system urging the company to sever its relationship with Breitbart, the site that former editor and now–Senior White House Advisor Steve Bannon once called “the platform for the alt-right.” Others are taking even stronger stands.

“Without naming names, I can attest that several employees have come to me in the past month questioning this exact point and I’ve stopped them from leaving the company,” one employee wrote on an email chain of worried Amazon employees.

Despite this internal unrest, Amazon has given no indication that it is changing its advertising relationship with Breitbart. Responding to the complaint ticket, Amazon’s ad team said it would not block the site from its program and closed the ticket from further responses.

In the online world, relationships between advertisers and publishers are not so straightforward as many people unfamiliar with the digital publishing industry might think. Rather than specifically buying ad space on particular web sites, advertisers often place ads through third-party ad exchanges, who programmatically fan those advertising buys out to their network of member sites. In Amazon’s case, that means Amazon customers may encounter Amazon advertisements on any of a number of different sites they visit (including Breitbart), while non-Amazon customers may never see any Amazon ads at all (on Breitbart or elsewhere).

So, in this case the level of Amazon’s advertising on Breitbart is largely driven by how many Amazon customers choose to visit Breitbart, not by how much money Amazon chooses to allocate to placing ads on that publisher’s site. Still, Amazon could choose not to do business with ad exchanges that include Breitbart among their clients, or possibly in some cases instruct those exchanges to exclude Breitbart from their ad placements.

Amazon has not yet responded to our request for comment about their advertising policies regarding Breitbart or whether they plan to alter them, but BuzzFeed noted that as of early February 2017, the online retailer was seemingly not inclined to take any action in that regard yet:

Amazon’s Associates program’s rules explicitly state that publishers using its advertising API may not “promote discrimination,” a line item that a number of Amazon employees feel Breitbart violates.

“As per guidance from PR/Policy/Legal, the DA team are not blocking breitbart.com,” Amazon’s ad team wrote. “As per prior guidance ‘our customers are choosing to go there. It is not our place to assume why they’re going there, or impose our own standards.’” The ad team did specify that it was looking into a “longer term solution to use a 3rd party brand safety which may block amazon ads from showing up on certain pages on sites like Breitbart in the future.”