WASHINGTON — Being shunned can have its upsides.

Most business school professors would probably advise against getting blackballed by your own party right out of the gate when starting a political consulting firm.

But winding up on the wrong side of the Democratic Congressional Campaign Committee has turned out to be good for business for Rebecca Katz, who was a top adviser to former Senate Majority Leader Harry Reid and to New York City Mayor Bill de Blasio. Katz started a new firm in February in part to work for insurgent progressive candidates and she's not alone.

"The DCCC blacklist backfired spectacularly because not only did it unite candidates behind a common cause, but because it connected us with candidates who never would have found us otherwise," Katz said, adding that business has been so good she has had to turn away prospective clients. "We're already in the black, and I feel like I'm on the right side of history."

The DCCC, the official campaign arm of House Democrats, said this spring it would cut off political consultants who work for a candidate who runs against an incumbent Democratic member of Congress.

The DCCC is trying to protect its members, who contribute much of the committee's funds, after insurgents Alexandria Ocasio-Cortez and Ayanna Pressley defeated longtime incumbents in primaries last year.

"The core mission of the DCCC is electing House Democrats, which includes supporting and protecting incumbents. To that end, the DCCC will not conduct business with, nor recommend to any of its targeted campaigns, any consultant that works with an opponent of a sitting Member of the House Democratic Caucus," reads the committee's vendor application.

Because the DCCC controls hundreds of millions of dollars and serves as a key matchmaker between candidates and consultants, its recommendations are vital for those who make their living off of campaigns.

But now, there's a small but growing ecosystem of professional political operators who are willing to buck the party and proud to call themselves members of what they dubbed the "blacklist" — though the DCCC says it has never used that term.

Justice Democrats, the insurgent-left group that recruited Ocasio-Cortez, started a website called the DCCCBlacklist.com, to act as a one-stop shop for candidates looking for strategists, field organizers, advertisement makers, tech vendors and more.

"What we're trying to build for the long term here is a party within the party," said Waleed Shaheed, the spokesperson for Justice Democrats. "It can be really really hard for primary challengers to find help because everyone's afraid that they’re going to get cut off. This was a way to help progressive primary challengers to find consultants and staff."

Senate Republicans have implemented a similar policy that's received less attention and some conservative consultants have carved out a niche working for anti-establishment candidates.

Sam Haas, the co-founder of Slingshot Strategies, said, "We have candidates contacting us on a near daily basis who mention that they first heard about us from the blacklist."

And he argued that prohibition actually has actually created "not just an incentive but really a necessity for groups like ours to do more primary challenges" to stay in business. "So, ironically, we are undoubtedly working with more Democratic primary challengers than we would being blacklisted by the DCCC," he said.

Alex Lawson, a co-founder of the new consulting firm Strategy & Hustle, said his company had gained clients by joining the Justice Democrats' list.

"Now if there's a primary challenger, they know exactly where to go look,” he said.

Jake DeGroot, who co-founded a new company to market the smartphone-based organizing tool he helped develop for Ocasio-Cortez' campaign, said he wanted to add his company’s name to the Justice Democrats’ "blacklist" even though he doesn’t think the DCCC's policy applies to tech vendors like his company.

"If anything, being identified as part of the movement standing up against the DCCC blacklist has been a positive thing in our relationship with our customers," said DeGroot, whose company also worked for Tiffany Caban, whoran for Queens, New York, district attorney. The results aren't official yet in that close contest as votes are being recounted.

The DCCC declined comment to NBC News, but previously released a statement from executive director Allison Jaslow saying, "The DCCC is responsible for protecting and growing our House majority, but I also know that we have the ability to set the course for the future of the Democratic Party while we're doing that."

Still, even those who wear the "blacklist" scarlet letter like a badge of honor don't like the policy and wish it would be changed.

"Our view is that having so many new people from diverse backgrounds deciding to run for office as Democrats today is a wonderful thing, and we should be doing everything we can to support and encourage them," said Jim Pugh, the founder and CEO of Share Progress, which joined the "blacklist." "It's very disappointing to see the DCCC send a message to these new candidates that 'you aren't welcome here.'"

And from a business perspective, primary candidates are only a tiny sliver of the overall pool of candidates out there. The ones running against Republicans will invariably raise and spend far more money, making them far more lucrative clients.

So while some consultants have done well on the "blacklist," others have been forced to choose between working for a primary challenger and risking the rest of their business.

Mary Newman, who is challenging moderate Rep. Dan Lipinski, D-Ill., in a Democratic primary, said much of her team abandoned her after the DCCC's policy went into effect.