A political heavyweight is joining in the fight over the Dakota Access Pipeline in Morton County.

Democratic Senator Bernie Sanders and four other senators are asking President Obama to halt construction on the pipeline.

Sanders says he is speaking out after the federal appeals court denied the Standing Rock Sioux's motion for a temporary hold on construction.

The Vermont senator and other lawmakers want a full environmental review of the pipeline's path before construction can continue.

In the meantime, a Wisconsin sheriff says he is planning to rotate three teams of Dane County deputies over the next three weeks to the pipeline protest site.

His group is responding to the call for help from the North Dakota Department of Emergency Services.