Marn'i Washington reportedly advised disaster assistance teams in Florida responding to Hurricane Milton to avoid homes that had yard signs supporting Trump.
Washington, who was fired earlier this month, has since claimed that the orders came from supervisors at FEMA.
In a statement, Tillis and Budd said the allegation raised grave concerns about potential widespread politicization of disaster relief.
"FEMA's mission is 'helping people before, during, and after disasters.' When a natural disaster overwhelms state and local resources, FEMA is the option of last resort to help American families rebuild their lives in times of great distress and upheaval. For a FEMA employee to withhold aid or support from a household due to political affiliation is unacceptable and frankly reprehensible. While there are many dedicated public servants who are working around the clock to help disaster survivors at their most vulnerable point, it is clear that FEMA has fallen well short of its core mission to provide disaster relief to all Americans impacted by a natural disaster," the senators wrote in a letter to FEMA Administrator Deanne Criswell.
Read the full letter here (.pdf)
Seventeen other Republican senators also signed the letter.
"While we appreciate your swift condemnation of these actions and termination of the responsible employee, your former employee has made subsequent claims that this was not an isolated incident, even happening in western North Carolina after Hurricane Helene brought devastating rains and floods the likes of which we have never seen," the senators continued. "The idea that citizens, whose tax dollars fund FEMA's Disaster Relief Fund (DRF) and pay FEMA officials' salaries, may be purposely excluded from vitally needed aid is chilling and further erodes many people's already tenuous trust in this administration.
"We demand answers, accountability, and transparency to hold your agency accountable to the American people and ensure that FEMA employees are providing support to all victims," the senators concluded. "Given the shocking and reprehensible nature of these allegations, our constituents deserve immediate answers and maximum transparency. As members of Congress, we are committed to holding those responsible accountable and making sure that rank weaponization against the American public is never tolerated."
After Washington was fired, Criswell released a statement saying, "This is a clear violation of FEMA's core values & principles to help people regardless of their political affiliation. This was reprehensible."
Washington told CNN that she has not been asked to appear before lawmakers, but that she would be willing to do so.
NOTE: Video is from a previous report.