Elon Musk, who U.S. President-elect Donald Trump has tapped to oversee a government cost-cutting effort, acknowledged that his declared goal of cutting $2 trillion in spending from the $6.8 trillion federal budget would be a long shot.

Elon Musk walked back his previous claim that he could cut at least $2 trillion from the federal budget, saying Wednesday that half that amount would be “an epic outcome.”