David Karpf is an Assistant Professor in the Rutgers University School of Communication and Information, as well as a Faculty Associate in the Eagleton Institute of Politics. His new book, The MoveOn Effect: The Unexpected Transformation of American Political Advocacy, came out May 30. He also spoke at Personal Democracy Forum 2012.

[UPDATE: Change.org announced on Monday night that it would be concluding its partnerships with Michelle Rhee's StudentsFirst and Jonah Edelman's Stand for Children, citing feedback from their fellow progressives. This particular dilemma of success has now reached a conclusion.]

Online petition juggernaut Change.org has become the target of an online petition effort.

Whoa.

Meta.

This weekend, a schoolteacher from Chicago launched a petition at SignOn.org* urging CEO Ben Rattray to “Stop Supporting Union-Busters.” So far it has over 3,700 signatures, but attention is rising. That’s because Rattray’s company is at an inflection point: rooted in progressive politics but structured as an open and for-profit platform, it’s now faced with a clarifying choice about its values and mission.

As techPresident’s Micah Sifry reported weeks ago, Change.org has had a tremendous year. In an era when social change organizations are finding it increasingly difficult to support large staff overhead, Change.org now has 140 staffers and will likely hire more. It has over 13 million users who start approximately 15,000 new petitions per month on subjects ranging from neighborhood issues to global human rights. While Change.org appears to have an implicit partisan cast, the company has managed to be both “open” and “progressive” in its early years. Now that it is also “big” that may no longer be the case. Here’s why.

As Micah wrote, what makes Change.org different is a team of professional campaigners that support popular issues on Change and work to help them go viral — something other petition sites don't offer. Change.org is able to pay these organizers by accepting sponsored petitions that let nonprofits, political campaigns, and “social good businesses” reach a larger audience and acquire new email addresses on a cost-per-acquisition basis.

Company officials have outlined a client policy designed to prevent the most obvious conflicts of interest: “We accept sponsored campaigns from organizations fighting for the public good and the common values we hold dear – fairness, equality, and justice. We do not accept sponsored campaigns from organizations that consistently violate these values, support discriminatory policies, or seek private corporate benefit that undermines the common good.”

It’s a big Internet. Sheriff Joe Arpaio, Birthers, and the National Organization for Marriage can go elsewhere for their e-petition needs.

But Change.org's current mess didn't begin with something as clearly incendiary as immigration or gay marriage. Instead, the outcry began thanks to a petition from Stand for Children, a nationwide advocacy organization that pushes for changes to teacher hiring, tenure, and other education policies at the state level. The petition in question was titled “Tell Chicago Board of Education and Teachers’ Union: Get Back to the Table,” and was prompted by a strike-authorization vote. Stand For Children can call that school reform, but the AFT and other progressives call it union-busting.

For Change.org, success has created a real dilemma. It is starting to reach the boundaries of the market for progressive-leaning partner organizations. If the organization rejects sponsored petitions from education reform organizations, it needs to reassess its growth expectations.

On the other hand, if Change.org continues to partner with StandForChildren.org, it should expect a slippery slope of future petitions. There are plenty of grey areas around conservative causes. Supporters of Wisconsin Gov. Scott Walker, for instance, swore they were not “anti-union,” merely “pro-fiscal responsibility.” There’s plenty of risk to the business side of the company down that path as well. Progressive activists have become particularly adept at corporate campaigning. While the front-page authors at DailyKos treated this current petition with a whimsical “how meta is this?” it isn’t hard to imagine organized outrage in the future.

Change.org's current issues are ones of scale and are faced by all online organizations that rely on user-generated content. As an organization passes from the early majority into the late majority stages of diffusion, new players start to arrive, seeking to convert the site’s popularity toward their own ends. Sites as diverse as Wikipedia, MySpace, CraigsList, and DailyKos have all faced their own version of the “valuable real estate problem.”

Simply formulated, once your site becomes a source of sustained traffic and attention, new sets of motivated actors will try to do something with it that your community doesn't like and hadn't tried to do before. That creates a very real threat. In 2007, MySpace faced an avalanche of spambot profiles. The company bungled its response, creating an opening that Facebook’s Mark Zuckerberg was happy to exploit. Openness is a lot simpler when only a few niche publics know your name.

There is no easy answer for Rattray and Change.org. They want to be open, they want to promote their own values, and they want to continue growing. Balancing those goals has just gotten tougher, specifically because of their year of success.

This post has been updated to include the number of signatures on the SignOn.org petition.

*SignOn.org is a competitor of Change.org, run by MoveOn.org.