WASHINGTON — U.S. Sen. Tom Tillis (R-NC) is on a mission.

He wants to uncover the ”sinister” reasons why some powerful tribal nations and 6 of his GOP U.S. Senate colleagues worked to block his efforts in the 117th U.S. Congress to federally recognize the Lumbee Tribe in his state.

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The senator himself reported on the Senate floor just before Christmas that all Democrats in the Senate were supportive of his amendment to the National Defense Authorization Act to do so, but that 6 GOP colleagues — prompted, it seems, by strategic lobbying from specific tribes — blocked his legislation.

U.S. Sen. Cindy Hyde-Smith (R-MS) was the one who put the nail in the coffin of Tillis’ bill with her objection to it — which she did not explain — during the amendment’s voting process. (See video below, courtesy of Forbes.)

Tillis said he respects Hyde-Smith after her objection — yet he vowed to find out why specific tribes apparently forced her hand.

“I want every tribe who has objected to this — while the majority of Native American tribes support it — know that we’re going to have a lot of quality time together over the next two years,” Tillis said after his colleague’s action.

140 of 574 federally recognized tribes reportedly signed on to letters to Congress, saying that they opposed inclusion of tribal recognition provisions in the Defense bill, specifically for the Lumbee Tribe and the state-recognized MOWA Band of Choctaw Indians in southwest Alabama.

Lumbee citizens, meanwhile, have been fighting for their recognition since colonial times, Tillis argued, and he believes the tribe has a distinct culture, language and has taken every bureaucratic step necessary to become federally recognized.

He also said Lumbee citizens disproportionately serve in the U.S. military despite the “disrespect” the federal government has shown them over centuries.

The Lumbee Tribe earned federal recognition from the U.S. Congress in the 1950s, but it was quickly stripped away by the same body, which was in a tizzy of an Indian termination mode at the time.

Tillis’ legislation received “huge bipartisan support” in the U.S. House this time around, he noted, “but for some reason, when it comes to the Senate, it goes to die, and I don’t understand that.”

“In fact, I’m going to spend a lot more time trying to understand it,” Tillis promised on the Senate floor on Dec. 20. “I’m going to try to understand why the Chickasaw, the Choctaw and the Cherokee — the Eastern Band [of Cherokee] in my own state — oppose it.”

“Some of them say because [it’s about] the integrity of the recognition process,” he continued, vowing to discuss the matter with the tribes in question. “I don’t believe that.”

“I believe that there is something more sinister involved in their objection to the Lumbee being recognized,” he said.

Below are 5 commonly discussed reasons why the Lumbee Tribe has faced an uphill battle for the past 130 years or so in gaining recognition:

• Some say that racism toward the tribe is the ultimate culprit, since many of its citizens have mixed heritage with African Americans.

• Some say nearby tribes don’t want the Lumbee recognized because the tribe would then be eligible to conduct gaming — and that would create market competition that would cost nearby tribes casino money.

• Some tribes don’t want Lumbee recognized because that would limit the pot of federal funds available to all tribes.

• Some tribes say that no tribe should be recognized by the U.S. Congress without passing recognition tests created by the U.S. Interior Department, despite Congress’ Constitution-rooted plenary power over tribes. Some worry that similar scenarios could play out in favor of many more state-recognized tribes nationwide, if Lumbee creates a major precedent.

• Finally, some tribes believe Lumbee and others state-recognized tribes are not real tribes, or Interior would have already recognized them. However, Interior has had many political reasons over the years for not recognizing particular tribes, and Lumbee has faced its share of unfair treatment from the federal agency, according to Lumbee citizens.

If recognized by the federal government, the Lumbee Tribe, with over 55k citizens, would be one of the largest, by population, east of the Mississippi River.

Lumbee tribal officials have grown so disappointed over the years with failed Democratic promises to recognize the tribe that some have turned to supportive Republicans, including Tillis and former U.S. Sen. Richard Burr (R-NC), who retired from the body at the end of the 117th session.

Former President Donald Trump also notably made a trek to Lumbee lands during his failed 2020 bid for re-election, promising he would support their recognition if they voted for him. And they did in percentages that beat current President Joe Biden, which was a surprise to many political commentators.

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Tillis further vowed to the Lumbee Tribe that “every week” he is in the Senate from here on out, he will work to “cast light on what are the legitimate objections to the Lumbee being recognized.”

“It is time for them to be recognized,” Tillis said. “I do want people to realize that this tribe deserves respect.”