White House Chief of Staff John Kelly will step down toward the end of the year, removing a key force for West Wing discipline from President Donald Trump's inner circle. White House aides believes that Nick Ayers, Vice President Mike Pence's chief of staff, will be named acting chief of staff, two aides said. Ayers has emerged as a favorite to replace Kelly; Trump has recently taken the unusual step of inviting Ayers to accompany him on Air Force One, even without Pence present, people familiar with the situation said.