Advocates for D.C. statehood have tried lobbying Congress. They’ve tried rallies, protests, T-shirts and license plates. There’s an ongoing effort to collect a million signatures for a petition.

And this week, in the latest and perhaps oddest twist in the pursuit of D.C. statehood, one of the District’s “shadow senators,” Paul Strauss, is in Europe, trying to persuade a little known organization of nationless ethnic groups to accept the capital of the world’s most powerful country into its ranks.

The Unrepresented Nations and Peoples Organization (UNPO) — not to be confused with the United Nations or its affiliates — brands itself as an advocacy group that unites “indigenous peoples, minorities, and unrecognized or occupied territories” that are “not adequately represented at major international fora, such as the United Nations.” And Strauss thinks the group, which includes a handful of active separatist groups, would be a good fit for the District.

“At first blush, we may not really be their typical candidate,” said Strauss, a corporate lawyer who serves as one of two elected shadow senators, or formal lobbyists for D.C. statehood. “So I have to make a case to this group that our territory meets the criteria for membership.”

Strauss, who traveled to Brussels on Wednesday night to argue for the District’s inclusion, believes that the move will draw attention to the city’s lack of representation. District residents are subject to federal income taxes but do not have voting representation in Congress.

Washington is the only jurisdiction in the United States that needs congressional approval to pass a law or budget. Yet the District’s overwhelmingly liberal lawmakers and activists have found relatively little support from elected Democrats on the national level, including President Obama, in their effort to change the status quo.

Strauss, therefore, makes the argument for UNPO inclusion like this: “Our lack of statehood effectively disenfranchises us in international bodies.”

“We’re petitioning to join as New Columbia, because that’s our aspirational empowered name,” he added.

The UNPO’s 44 members would make some interesting, if not particularly useful, bed­fellows.

They include the Acheh-Sumatra National Liberation Front, an Indonesian separatist group; the Ogaden National Liberation Front, a Somali separatist group in Ethi­o­pia that the State Department has accused of human rights abuses; and the separatist state of Abkhazia, which in the early 1990s fought a war of secession from the former Soviet republic of Georgia, a U.S. ally, and which is currently occupied by Russia.

Others, like the Haratin of Mauritania, the Tibetans in China and the Crimean Tatars in Russia, are religious or ethnic minorities that have struggled against slavery, repression and state-sanctioned violence in some of the world’s poorest and most conflict-ridden territories.

“These are countries with poor human rights records in general, especially for minority groups who have little recourse in the judicial system to protect their rights,” said Paul Stronski, a senior associate and Russia expert at the Carnegie Endowment for International Peace, a Washington think tank. “That someone would [compare] the plight of the District to that of some of these minority groups just boggles my mind.

“To me, it sounds more like a political stunt, and a not very tasteful one at that,” he added.

Strauss, who spoke by phone from Brussels on Wednesday, admitted that he didn’t know much about many of the District’s prospective new club mates, though he was able to list some, such as the Khmer Krom, whose representatives were staying in his hotel.

“Um, they —” he said, then paused, when asked about the Southeast Asian ethnic group. “I’d have to refer to that map.”

But joining the UNPO doesn’t require throwing your support behind any of its members’ causes, Strauss said. It’s a venue for advocacy. It’s a source of publicity. It’s something to draw attention to the District’s taxation without representation.

“There is hypocrisy with us going around and saying we’re this great democracy, when the residents of our capital don’t have representation,” explained Anise Jenkins, executive director of Stand Up! For Democracy in D.C., a statehood activist group. Jenkins said she didn’t know about Strauss’s trip but approved of it.

“I think anywhere we can spread the word about our lack of democracy here is appropriate,” Jenkins said.

Strauss said that tax dollars — part of the New Columbia Statehood Commission’s budget — paid for his trip but that his upgrade to business class came from his own frequent-flier miles.

He said he expected the UNPO to decide Saturday on the District’s admission.

And though Strauss didn’t publicize his trip and Mayor Muriel E. Bowser (D) said through an aide Thursday that she didn’t know about it, several District lawmakers agreed that the gesture could have a positive impact.

“Do I want to see the U.S. tarnished by an international group lumping us in with other governments that are reprehensible? No,” D.C. Council Chairman Phil Mendelson (D) said. “But I think it’s a fact that we’re the only nation’s capital in the free world where people have no voting representation in the nation’s legislature.”

The District should “be constantly looking for different strategies that raise awareness,” he said.

Council member David Grosso (I-At Large), who studied international law, didn’t think D.C. necessarily qualifies as “unrepresented.” After all, D.C. residents can vote for president, they have U.S. citizenship and they elect local lawmakers, he said.

“But anytime you can have an opportunity to try to educate whoever it is on D.C.’s issues when it comes to insufficient representation in Congress, I think that’s really valuable,” Grosso said. “I don’t have a problem with him going to Brussels to do that.”