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.

Musk has been so aggressive in pushing his views about Trump’s second term that he’s stepping on the toes of Trump’s transition team and may be overstaying his welcome at Mar-a-Lago, Trump’s home in Palm Beach, Florida, according to two people familiar with the transition who have spent time at the resort over the past week.

President-elect Donald Trump made good on one of his campaign promises Tuesday night when he officially appointed billionaire Elon Musk to lead the new “Department of Government Efficiency,” along with entrepreneur Vivek Ramaswamy.