US President-elect Donald Trump will not pursue charges against Hillary Clinton over her use of a private email server.
Donald Trump and Hillary Clinton at the second debate of the US presidential campaign. Photo: AFP
Mr Trump had threatened to jail his rival for the presidency, and at his rallies his supporters often chanted "Lock her up".
Trump senior adviser Kellyanne Conway said the president-elect was backing down from his campaign promise so Mrs Clinton could "heal".
"Hillary Clinton still has to face the fact that a majority of Americans don't find her to be honest or trustworthy, but if Donald Trump can help her heal then perhaps that's a good thing," she said on MSNBC.
The FBI has cleared Mrs Clinton of any wrongdoing over her use of a private email server while she was US Secretary of State.
Regardless of whether Mr Trump opts to appoint a special prosecutor, as he vowed during the campaign, Congress can pursue its own investigations.
Republican chairman of the House Oversight and Government Reform Committee, Jason Chaffetz, has said he will continue investigating Mrs Clinton's use of a private server.
But Ms Conway indicated Mr Trump would frown on that.
"When the president-elect, who's also the head of your party now, tells you before he's even inaugurated he doesn't wish to pursue these charges, it sends a very strong message - tone and content - to the members," she said.
The right-wing Breitbart News Network, which aligned itself with the New York billionaire early in the election, swiftly decried the climbdown as a "broken promise".
The FBI director shook up the presidential race when he announced a new inquiry into Mrs Clinton's private email server shortly before the election, reviving an investigation that had been completed in July.
In a call to donors following her shock election defeat, Mrs Clinton blamed her loss on the FBI director's last-minute intervention.
Mr Trump has been holding meetings since his election victory to build his administration and fill senior posts before he takes office on 20 January.
He has not held a news conference to talk about his priorities since his election, although on Monday he issued a short video message on his plans for his first days in office.
- BBC / Reuters