Nick Ayers, US President Donald Trump's purported choice to be his next chief of staff following the dismissal of four-star general John Kelly, has refused the offer, Reuters reported Sunday, citing sources familiar with the matter.

On Sunday, the US president said that a decision would be made soon.

Media reports of tensions between the president and his chief of staff had escalated to an extent that the two have not spoken to each other for days. Kelly, who assumed the post in the summer of 2017, is the first member of Trump's administration interviewed by Special Counsel Robert Mueller who was not part of the president's campaign or transition team. 

The White House chief of staff responded "to a narrow set of questions" from investigators on charges of obstruction of justice. The White House earlier this summer objected to the request from Mueller's team for an interview with Kelly.

Media reports suggested that Vice President Mike Pence’s Chief of Staff Nick Ayers was originally Trump's top pick for the post, but a disavowal of the offer by Ayers has again thrown the matter open.

Meanwhile, Nick Ayers, the 36-year-old chief of staff to the Vice President, tweeted Sunday that he "will be departing at the end of the year but will work with the #MAGA team to advance the cause," referring to Trump's campaign.