On Tuesday afternoon, with much of the political world focused on questions about Hillary Clinton's pneumonia, Sen. Bernie Sanders (Vt.) appeared in front of the White House to rally against the Dakota Access Pipeline. Flanked by Native American leaders, Sanders was back in campaign mode, pledging "the end of the exploitation of Native American people and the respect of Native American rights."

"I am calling for a full environmental and cultural impact analysis of the pipeline," said Sanders. "When that analysis takes place, this pipeline will not continue."

As a candidate for president, Sanders campaigned hard in states with large Native American populations and reservations — and frequently, he won. After meeting with tribal leaders in the Dakotas, Sanders began critiquing the government's treatment of Native Americans in every speech, promising that "this campaign is listening," and raising the profile of local fights against energy exploration.

The Dakota Access Pipeline was at the center of one of those fights. Sanders's Tuesday speech was the highlight of a national "day of action" to raise the profile of the 1,172-mile pipeline, now under construction. In July, after Sanders's campaign ended, the Standing Rock Sioux Tribal Council sued to stop it, arguing that the pipeline was cutting through sacred land. Dozens of tribes have descended on North Dakota to aid in their resistance, which last week included clashes between protesters and Dakota Access's private security workers.

But the issue has hardly pierced the veil of domestic politics. While Green Party presidential candidate Jill Stein traveled to support protesters in North Dakota, neither Donald Trump nor Hillary Clinton has taken a position on the pipeline. The only question posed to President Obama about the pipeline came at a town hall forum in Laos, where a questioner from Malaysia asked specifically what the president could do to protect the native lands from the pipeline.

"The way that Native Americans were treated was tragic," said President Obama, dodging the question. "I can't give you details on this particular case — I'll have to go back to my staff and give you details."

Anti-pipeline activists take solace in their own experience — the fight against the Keystone XL pipeline. Just as political pressure convinced the Obama administration to slow down the pipeline's approval with environmental tests, activists, like Sanders, hope that a fresh analysis of Dakota Access could halt construction. With Democrats shut out of power in Congress, the so-far-reluctant White House is the only entity that might be able to help.

On Tuesday, several more Sanders-backed candidates advanced in primaries in New York and Rhode Island, and Sanders's group Our Revolution announced a new endorsement: Chase Iron Eyes, a member of the Standing Rock Sioux Tribe now running as the heavy underdog for North Dakota's solitary House seat.