Last week, following a vote in the U.S. House that the Rosebud Sioux Tribe described as "an act of war," the Senate failed to authorize construction of the Keystone XL pipeline. When the vote closed, an honor song rang out over the Senate gallery. Greg Grey Cloud, a member of the Crow Creek Sioux Tribe, sang in recognition of the 41 senators who voted against the looming threat that Native people have dubbed the "black snake," a menace to the environment, private property rights and tribal sacred sites. I was shocked and saddened that Jon Tester wasn't among them, that Montana's senior senator and the chairman of the Senate Committee on Indian Affairs failed to stand with us at such an important moment.

I'm not what you'd call politically minded. I have opinions, sure, and an Indian with an opinion is a de facto activist, but the first time I registered to vote in anything other than a tribal election was to cast my vote for Tester in his 2012 reelection bid. He was a strong supporter of the Keystone XL expansion even then, but I hoped he'd learn more about the project and change his mind. His staff seemed willfully ignorant that his support of the pipeline presented any conflict between his labor and Indian constituencies; I knew better.

Native people, my family among them, have spoken out against the expansion of the pipeline since it was first proposed in 2008. We stand in solidarity with our First Nations relatives in Canada who have led the fight against the exploitation of the tar sands, and in recognition of the threat the black snake poses to our groundwater, air and sacred sites. And our movement is gaining momentum.