Heads were always likely to roll in the White House after Republicans endured one of their worst ever midterm election losses under Donald Trump.

On Friday, Susie Wiles became the first to go, with the President announcing his chief of staff would move into a new role within his political operation.

Her replacement: Stephen Miller, one of Trump’s longest-serving and most loyal aides.

Miller has been a frequent target for critics of the Trump administration, branded an “extremist” by some for his role in formulating the President’s aggressive immigration crackdown.

His appointment is likely be viewed with suspicion by Democrats, who will need to coordinate with the White House to have any chance of overcoming Trump’s presidential veto on legislation.

An early backer of Trump’s agenda

Miller has been working with Trump since the former property developer first entered politics, joining his 2016 presidential campaign as a speechwriter and policy advisor.

Prior to that, Miller had worked for ultra-conservative Alabama Senator Jeff Sessions – the first Republican senator to back Trump’s campaign.

After Trump won office, he appointed Miller national policy director and gave him broad oversight of the administration’s priorities.

Among his key influences were backing Trump’s extensive use of executive power and shaping the President’s hardline immigration policies, both areas which prompted fierce criticism.

Miller embraced Trump’s claims immigrants had driven up rates of violent crime and pushed for mass deportations of non-citizens.

He also oversaw the policy of separation for families subject to deportation proceedings and was credited with devising a controversial travel ban targeting nations with large Muslim populations.

Miller remained close to Trump throughout his spell out of office, supporting the President’s false claims of voter fraud in the 2020 election and working on revising his 2024 campaign and future agenda.

Upon Trump’s return to the White House in 2024, Miller was elevated to deputy chief of staff for policy and homeland security advisor.

Major enforcement operations by Immigration Customs Enforcement (ICE) agents, mainly targeting Democrat-led states, followed and generated even more controversy.

Miller was among a group of senior Trump officials who branded Alex Pretti, a Minneapolis local killed by ICE agents, an “assassin” and “domestic terrorist”.

The comments sparked intense backlash, with Miller later walking back his remarks by acknowledging the agents “may not have been following” correct protocolls.

Despite garnering a negative public opinion, Miller remained a fierce advocate of the White House’s agenda.

Branding Democrats “extremists, freaks and America-hating lunatics” on social media, Miller staunchly defended the President’s record in office, with a particular focus on the controversial immigration crackdown instituted across a number of states.

In a statement following his appointment Miller said he was “honored beyond words” to become Trump’s chief of staff.

“The mission now is more clear than ever: Fight with all of our soul to support our President and defend this magnificent Republic,” he added.

Combative instincts set up potential fights with Congress

In the wake of Republicans’ midterm losses, Trump had initially suggested he could seek to reach compromises with the incoming Democrat leadership in Congress.

In a series of subdued interviews on election night, the President acknowledged his opponents had done a “good job” campaigning against his administration and said he believed they would seek to “make a deal” with him to pass legislation.

However, Miller’s immediate call to arms is likely to increase suspicions among senior Democrats Trump instead intends to play spoiler for his remaining two years in office.

That was the view taken by veteran Democrat strategist David Axelrod, who suggested Miller’s appointment would act as a roadblock to establishing a working relationship between Congress and the President.

“For those who hoped the @POTUS might pivot to work with the incoming Congress, the appointment of Miller is a bucket of ICE cold water,” he wrote in a social media post.

Hakeem Jeffries, the Democrat House leader widely expected to become Speaker, went further.

“Stephen Miller is a dangerous xenophobe and reckless extremist who has American blood on his hands,” he tweeted following news of the appointment.

“His presence in government should be eradicated like a malignant tumor.”

Trump, though, was quick to defend his appointment.

Miller “gets it” he told reporters on Friday, adding: “He’s a very good manager. He’ll do a great job”.

However, after an election widely seen as a repudiation of many of the policies Miller was viewed as instrumental in implementing, some are less sure.

Republican Senator Thom Tillis has blamed Trump’s new chief of staff for “some of the dumbest proposals” to come out of the White House, adding Miller was “incompetent”.

Meanwhile, Anthony Scaramucci suggested the appointment was an act of self-sabotage.

“Trump saw the midterm results and decided elevating Stephen Miller is the answer. He is even more delusional than I thought,” Trump’s one-time press secretary posted to social media.

“Or maybe he actually wants to finish destroying the @GOP?”