Breaking: Trump to replace chief of staff with hardline deputy Stephen Miller

Donald Trump has announced that his chief of staff Susie Wiles will be replaced by her hardline deputy Stephen Miller on Monday.

The US President made the announcement on Friday, local time, in a social media post.

Mr Trump thanked Ms Wiles for doing an "outstanding job" and said she would move to a different role in his "political operation".

In reality, the switch sidelines one of his most senior staff members.

"I want to thank her for her service as chief of staff," Mr Trump's post read. "She has done a great job!"

Analysts have widely speculated Mr Trump will reshuffle his administration after his Republican Party's disastrous performance at this week's midterm elections.

In March, Ms Wiles announced she would be taking time away from her role after being diagnosed with breast cancer.

Analysts have told the ABC they believe Mr Trump's administration lost its way after Ms Wiles's health battle began.

"Serving President Trump in the White House has been the honour of a lifetime," Ms Wiles said in a social media post on Friday, local time.

"I'm so proud to have been a part of what we've accomplished together from securing our border and cutting taxes to strengthening our economy and putting America First."

Mr Miller is best known as the architect of the Trump administration's immigration crackdown.

The 41-year-old has long helped shape immigration policy in the GOP.

He was Mr Trump's chief immigration advisor during the president's first term.

Before that, Mr Miller worked for Senator Jeff Sessions, who was renowned as one of the chamber's loudest and most uncompromising voices on the subject.

Most recently, Mr Miller has driven the push for mass deportations, pressing ICE leadership to raise arrest numbers and publicly telling officers they would have "federal immunity in the conduct of your duties".