U.S. New Mexico Sens. Tom Udall and Martin Heinrich appealed Wednesday to President Barack Obama to take action to protect the safety of demonstrators protesting the Dakota Access pipeline.  

Udall and Heinrich each wrote to the president citing examples of violence in North Dakota against Standing Rock Sioux Tribe members and demonstrators camping in the area, The Albuquerque Journal reported. 

“The current situation at Camp Oceti Sakowin is unsustainable and dangerous to everyone involved,” Heinrich wrote in the letter posted on his website. “I implore you to work with the Corps of Engineers and the Department of Justice to de-escalate the violence at the camp.”

The senators thanked Obama for his quick response to earlier confrontations between law enforcers and protestors.

“I appreciated that President Obama followed up by temporarily halting a portion of the project, while reviewing the permitting process for the river crossing, and pledging to hold consultation sessions with Tribes across the country,” Udall said in a statement.

Heinrich said he was thankful for the administration’s quick response but the renewed violence in the area involving “rubber bullets, tear gas, and water cannons” are putting the health of the demonstrators at risk. 

They expressed concern over the possibility of escalated tensions due to the Dec. 5 clear out date the Army Corps of Engineers imposed on the protestors staying in the area. 

“This arbitrary date is certain to escalate an already volatile situation and I would urge you to overturn this decision by the Corps of Engineers,” Heinrich said in his letter.

As incoming vice chairman of the Senate Indian Affairs Committee, Udall urged Obama to reconsider every option available to protect Tribal rights and land and rerouting the pipeline. 

“Protesters have a right to make their voices heard peacefully, and the Department of Justice should redouble its efforts to prevent civil rights abuses and prevent the situation from becoming tragic,” Udall said in his statement. “Finally, all New Mexicans, Tribal members or not, know that water is life, and so I am calling on the president to take action before the end of his term to find a positive resolution to this situation by considering all available options to protect Tribal resources, including re-routing the pipeline to better safeguard water quality.”

Udall tweeted a copy of his full letter on Wednesday.

I’m asking @POTUS to take urgent action on #DAPL to protect Tribal rights & the safety of protesters #waterislife https://t.co/m0TaCc535y pic.twitter.com/vFnNPL9Q2Q

— Tom Udall (@SenatorTomUdall) November 30, 2016