(CNN) The White House has requested $1.25 billion in emergency funding to address the novel coronavirus, part of an effort to direct as much as $2.5 billion in total funds to bolster its response to the growing global crisis, according to a letter obtained by CNN.

"To this point, no agency has been inhibited in response efforts due to resources or authorities," Russell Vought, the acting director at the Office of Management and Budget, wrote in the letter to lawmakers requesting the funds. "However, much is still unknown about the virus and the disease it causes."

In total, Vought wrote, the administration expects "to allocate at least $2.5 billion in total resources" for the response effort. Much of that support would come from shifting funds already appropriated to other government agencies toward the effort.

Lawmakers said they were preparing for the administration's request to reach Capitol Hill, even as the final numbers were still in flux in advance of the letter sent Monday evening.

Senate Appropriations Chairman Richard Shelby, an Alabama Republican, told reporters Monday that his staff had been in discussions with the White House about the looming request.

Read More