Trump is expected to secure the nomination to run for reelection at the Republican convention starting on Monday.
Conway: Aide since day one.
Conway, a long-serving adviser to Trump known for sparring with reporters, announced Sunday she will step down to focus on her family.
Conway, 53, has been at Trump's side since day one, managing his 2016 campaign that catapulted the reality TV star into the world's most powerful office.
Her husband, conservative lawyer George Conway, is one of Trump's fiercest opponents.
National security
Trump has lost three national security advisers since taking office — John Bolton, H.R. McMaster and Michael Flynn.
Bolton was fired in September 2019, after disagreements with Trump on issues from Iran to North Korea and Afghanistan.
He published a tell-all book in June in which he said Trump was a one-term president and not fit for office.
Flynn, a retired lieutenant general, lasted only 22 days in the position. He was being investigated for his contacts with Russians when he was removed and eventually pleaded guilty to lying to the FBI.
Flynn's replacement, McMaster, also a lieutenant general, lasted barely a year.
McMaster never really clicked with the president, who bristled at his echoing the US intelligence establishment consensus that Russia meddled in the 2016 election.
Intelligence
Dan Coats, a former Republican senator from Indiana, stepped down as director of National Intelligence on August 15, 2019.
Coats was viewed as apolitical and enjoyed bipartisan support, but did not see eye to eye with Trump on a range of issues and at times appears to have been kept in the dark by his administration.
Homeland security
The departure, announced on April 7, 2019, of Homeland Security secretary Kirstjen Nielsen was a sign of Trump's determination to crack down on immigration.
Nielsen was reported to have had difficult relations with Trump, but although he criticised her work, she remained loyal.
Defence
Defence Secretary Jim Mattis announced on December 20, 2018 that he was quitting, criticising Trump's diplomatic strategy.
After the announcement of the withdrawal of US troops from Syria, the former Marine general was in a more awkward situation than ever, as he had fiercely opposed the move.
Foreign policy
Trump's first secretary of state, Rex Tillerson, was fired in March 2018, ending a rocky tenure for the former Exxon chief executive as the nation's top diplomat.
During Tillerson's brief stay, he frequently found himself out of the loop and caught unawares by policy shifts announced in Trump tweets.
Chief strategist
Steve Bannon
The architect of Trump's nationalist-populist political stance and his election victory, Bannon was nicknamed the Prince of Darkness and the Shadow President.
But his constant clashes with other Trump advisers became untenable, and Bannon left on August 18, 2017.
Three years later, on August 20, he was arrested for defrauding donors to a Mexico border wall fundraising campaign, and has said he is the victim of a "political hit job".