White House budget director Shalanda Young warned in a letter to Republican House Speaker Mike Johnson and other congressional leaders on Monday that the United States was running out of time and money to help Ukraine fight its war with Russia.
President Joe Biden's administration in October asked Congress for nearly $106 billion to fund ambitious plans for Ukraine, Israel and US border security.
Republicans control the House of Representatives with a slim majority, and funding for Ukraine has become politically controversial with some right-leaning lawmakers.
Young said in a letter released by the White House that cutting off funding and a flow of weapons to Ukraine would increase the likelihood of Russian victories.
"I want to be clear: without congressional action, by the end of the year we will run out of resources to procure more weapons and equipment for Ukraine and to provide equipment from US military stocks," she wrote.