You might not think the National Cannabis Industry Association, International Brotherhood of Electrical Workers and National Mining Association have much in common.
But they have this: Lobbyists for these organizations have donated money to the presidential campaign of Democrat Bernie Sanders , the self-described socialist who has regularly castigated special interests and the government influence industry.
In fact, nearly two-dozen federally registered lobbyists have given money to Sanders’ presidential campaign, according to a Center for Public Integrity  review of campaign finance records and data obtained from the Center for Responsive Politics .
Sanders has painted himself as a different kind of politician, running a different kind of campaign.
When he launched his presidential bid last May, he proclaimed : “Today, we stand here and say loudly and clearly that enough is enough. This great nation and its government belong to all of the people, and not to a handful of billionaires, their super PACs and their lobbyists.”
It’s a theme Sanders has revisited time and again — on the campaign trail, in advertisements and during debates against front-runner Hillary Clinton .
But unlike President Barack Obama, who refused campaign contributions from registered lobbyists , Sanders’ campaign confirmed it does not ban lobbyists from making contributions — even as Sanders has called  on the Democratic Party to maintain a ban , implemented by Obama, on lobbyists giving to the Democratic National Committee.
Campaign officials declined to say whether Sanders would return, or otherwise dispose of, contributions received from registered lobbyists. They also declined to say whether the campaign would change its policy regarding donations from registered lobbyists.
“One of the many messages our campaign has effectively sent to the political establishment of this country is that the American people have had enough of the billionaire class buying elections,” Sanders campaign manager Jeff Weaver told the Center for Public Integrity.
Added Mike Casca, Sanders’ rapid response director: "Bernie’s campaign is fueled by individual contributions averaging under $30 — not lobbyists bundling six figures at private events."
A Clinton campaign spokesperson did not immediately respond to a request for comment.
To be sure, lobbyist donations — about $3,200 overall — represent a tiny fraction of the more than $96 million  raised Sanders has raised for his underdog presidential bid.
About 70 percent of that sum comes from small-dollar donors who have given Sanders $200 or less.
Sanders’ anti-big money, anti-special interest mantra has resonated with many voters, who have lifted him to victory against Clinton in several primary and caucus contests .
The lobbyist cash the Sanders campaign has collected has come from traditionally left-leaning causes: labor unions, environmentalists, the American Civil Liberties Union.
For instance, John M. Walsh, a lobbyist for the International Brotherhood of Electrical Workers, contributed $500 to Sanders last year.
Other labor lobbyists giving Sanders money include Ian Hoffmann, a lobbyist for the American Federation of Government Employees, who contributed $235, and Michael Dolan, a lobbyist for the Teamsters, who gave $100.
Each lobbyist declined to comment.
Lobbyist Michael Correia of the National Cannabis Industry Association also donated $500 to Sanders last year. That’s tied for the largest amount among Sanders’ lobbyist contributors to date.
Correia, who also gave $500 to Republican Rand Paul , told the Center for Public Integrity he contributed to both presidential campaigns because it was an “opportunity to reward somebody” for being a leader on cannabis policy.
In November, Sanders introduced a bill  to decriminalize marijuana.
“I can understand when he uses the rhetoric about lobbyists or the power of corporations — I get that,” Correia continued, adding that lobbying the government is a constitutionally protected right. “I can proudly say that I’m a lobbyist … I’m doing something that I think is right and on the right side of history.”
That sentiment was reiterated by other lobbyists contacted by the Center for Public Integrity.
One Sanders-supporting lobbyist who refused to be quoted by name said: “I’m a good lobbyist” and insisted that “not all lobbyists are unethical.”
Most lobbyists who’ve contributed to Sanders’ campaign simply didn’t want to discuss their donations.
“Unfortunately, I can’t discuss my personal political affiliations on the record,” said Ian Thompson, a lobbyist at the American Civil Liberties Union who has given $170 to Sanders.
“I respectfully decline comment,” echoed Robert Henson, a lobbyist at Credit Union National Association who has donated $100 to Sanders.
Likewise, Amanda Aspatore, a lobbyist at the National Mining Association who has given Sanders $250, declined to discuss her contribution.
“I’m not going to comment on that,” she said.
Chris Zubak-Skees contributed to this report.
This story was co-published with Newsweek .