Virginia Rep. Frank Wolf is once again urging the Obama administration to do more to fight the humanitarian crisis in South Sudan.
The Republican lawmaker said the conditions in the area are rapidly deteriorating.
He cited a serious food shortage in the Nuba Mountains and an "alarming increase" in the number of those living in one refugee camp.
"Time is running out," he warned President Obama in a letter. "Lives hang in the balance. The marginalized people of these areas are yearning for our help."
Wolf holds Sudanese President Omar Bashir responsible for the crisis. He said the daily bombing raids are preventing Nuba residents from planting crops.
"Bashir is not only bombarding his own people, but is effectively starving them to death - using food as a weapon of war," Wolf wrote. "The blood of the Nuban people is on his hands."