WASHINGTON (AFP) - White House chief of staff John Kelly will be leaving by the end of the year, US President Donald Trump announced Saturday (Dec 8). That will make him the latest top official to exit the US leader's inner circle.

Dozens of White House aides - from Attorney General Jeff Sessions to press secretary Sean Spicer to chief of staff Reince Priebus - have either left or been sacked from their posts since Trump took office on January 20, 2017. Here is a sampling of senior departures:

Chief of staff John Kelly

Kelly, a retired four-star Marine Corps general, has been credited with helping restore a degree of order to the often-chaotic Trump White House. But in the process he clashed with members of the Trump clan, and at times infuriated Democrats with his blunt comments.

Trump, who once said he wanted his aide to stay with him until the presidential election year of 2020, had made it clear of late that the relationship had chilled. "At some point he's going to want to move on," the president said in mid-November.

Indeed, Kelly, 68, made it clear he did not always love the job - one of the most vital in any White House, quipping, "God punished me, I guess."

Attorney General Jeff Sessions

Sessions, a Republican senator from Alabama, was the first member of the Senate to back Trump's insurgent bid in 2015 for the Republican presidential nomination. After winning the presidency, Trump rewarded Sessions by naming him to head the Department of Justice.

But relations between the two quickly soured after Sessions recused himself from Special Counsel Robert Mueller's probe into whether the Trump presidential campaign colluded with Russia to get him elected. Trump personally attacked Sessions on several occasions for failing to protect him from the Mueller probe.

"I don't have an attorney general," Trump told Hill.TV in an interview in September. "It's very sad."

UN Ambassador Nikki Haley

Haley, who announced in October that she would leave the administration at the end of 2018, was a shining star of the administration from the start.

Thrust onto the international stage, she quickly became an astute advocate for Trump's foreign policy, using forceful language against North Korea, Syria and Iran.

The former South Carolina governor was also unafraid to speak her mind, often in fairly undiplomatic language, and built a reputation for standing up to Trump when she felt it was warranted. Her aggressive criticism of Russia won plaudits, even as she stepped beyond the position held by the White House.

Her resignation announcement last month sparked speculation about her political future, though she denied any plans to challenge Trump in 2020, saying she would remain loyal to the president.

National Security Advisor Michael Flynn

Michael Flynn, a retired lieutenant general, entered the White House with a cloud over him - he had been fired by Barack Obama as defense intelligence chief.

Flynn was also being investigated for his contacts with Russians and eventually pleaded guilty to lying to the FBI.

Flynn lasted only 22 days as national security advisor.

He was forced out on Feb 13, 2017 amid concerns that he could be compromised by false statements he made over his contacts with Russian officials and his paid lobbying for Turkey during the campaign.

Chief of Staff Reince Priebus

Reince Priebus, the former chairman of the Republican National Committee, was supposed to manage the White House workflow and control the door to Trump's office.

But Priebus, who was never a member of Trump's inner circle, couldn't manage the tweeting president himself, and the West Wing sank into chaos.

Priebus made his exit on July 31, to be replaced by retired Marine Corps general John Kelly, who has been credited with bringing a measure of discipline to the Oval Office - though some say his future is also in doubt.

Chief Strategist Steve Bannon

The architect of Trump's nationalist-populist campaign and his election victory, White House chief strategist Steve Bannon was nicknamed the Prince of Darkness and the Shadow President.

His economic nationalism became the lynchpin of Trump policies, even as many of his other ideas were rebuffed by policy rivals.

After Kelly arrived, Bannon's constant clashes with other advisors became untenable, as did his ties to the extreme right, which drew accusations that Trump fostered racists.

Bannon left on Aug 18.

Top Economic Advisor Gary Cohn

Gary Cohn, a former president of investment bank Goldman Sachs, resigned as Trump's top economic advisor on March 6, 2018 in protest against the president's decision to levy new global trade tariffs.

A long-time Democrat, Cohn had always been an uneasy fit in an administration propelled to power by strident nationalism.

Trump's decision to impose the steep tariffs on imports of steel and aluminum was the final straw for the former Wall Street banker.

The first eruption of tensions with Trump came last year when the president balked at condemning neo-Nazis and far-right extremists who had led a violent rally in Virginia in August. Cohn, who is Jewish, said he considered resigning.

Secretary of State Rex Tillerson

Rex Tillerson was fired by Trump on March 13, ending a rocky tenure as the nation's top diplomat for the former chief executive of Exxon.

Tillerson was frequently at odds with the mercurial president and Trump said that while the pair got along "quite well," they "disagreed on things" - notably the Iran nuclear deal.

During his brief stay at Foggy Bottom, Tillerson frequently found himself out of the loop and caught unawares by policy shifts announced in Trump tweets.

A top aide said Tillerson did not speak to the president before his firing was announced and was not given a reason for his dismissal.

National Security Advisor HR McMaster

HR McMaster, a lieutenant general in the US Army who gained fame for a landmark book blaming politicians for the American debacle in Vietnam, leaves his post on April 9.

Trump tweeted that McMaster "has done an outstanding job," but he never really clicked with the president, who bristled at the general lecturing on policy.

Perhaps the final straw came when McMaster, echoing the consensus of the US intelligence establishment, told a conference that the evidence was "incontrovertible" that Russia meddled in the 2016 election, drawing a public rebuke from Trump, who is hyper-sensitive to the implication that Moscow aided his victory.

Environment chief Scott Pruitt

On Thursday, Trump announced that scandal-hit Scott Pruitt had resigned from his post heading the Environmental Protection Agency.

"Within the Agency Scott has done an outstanding job, and I will always be thankful to him for this," added Trump, who gave no reason for Pruitt's departure.

He said the ex-chief's deputy - a former coal lobbyist - would take over Monday as the agency's acting head.

A former Oklahoma attorney general reported to have close ties to fossil fuel industries, Pruitt, 50, was the focus of multiple recent probes.

All the charges share a common thread: that he appears to have used the position he has held since February 2017 to enrich his own family's lifestyle in violation of federal law, while punishing subordinates who raised objections to his behaviour, or who failed to show sufficient loyalty to him.