President-elect Donald Trump and Elon Musk have big ambitions for making the federal government leaner and more efficient by reviewing its budget and operations from top to bottom.

Donald Trump joked he “can’t get rid” of Elon Musk as the billionaire continues to exercise influence over the president-elect. Trump declared Musk co-chair of the new Department of Government Efficiency on Tuesday with the Tesla and SpaceX CEO leading the agency alongside former GOP presidential candidate Vivek Ramaswamy.

Though he is not expected to formally fill a position in Trump's administration, Musk "is having just as much influence from the outside," per a CNN source