Trump reiterates "disappointment" in Attorney General

US President Donald Trump has once again publicly lashed out at US Attorney General Jeff Sessions, calling him "VERY weak" in a tweet on Tuesday.

Trump berated Sessions over what he deemed insufficient efforts in pursuing intelligence leaks and for failing to go after former Democratic presidential candidate Hillary Clinton over her private email server.

Sessions was one of Trump's earliest and most loyal supporters, but the Republican billionaire has turned on him publicly in the past week.

Rumours are rife that the former senator from Alabama will be replaced.

Trump has openly criticised Sessions for recusing himself from overseeing a federal probe into possible collusion between the Trump campaign and Russia to meddle in the 2016 US presidential elections.

Later, he again said he was "disappointed" in Sessions and reiterated that had he known Sessions would remove himself from the Russia probe, he would not have hired him.

"He should not have recused himself almost immediately after he took office and, if he was going to recuse himself, he should have told me prior to taking office, and I would have quite simply picked somebody else," Trump told reporters.

"Resolution soon"

New White House Press Secretary Sarah Huckabee Sanders indicated Tuesday that Trump was not going to change his mind, and her boss, communications director Anthony Scaramucci said, "We'll get to a resolution soon."

US presidents normally go to great pains to avoid being seen as influencing ongoing or possible investigations, making Trump's attacks on Sessions all the more extraordinary.

With pressure mounting from the investigation led by special counsel and former FBI director Robert Mueller, Trump has sought to revive an election year controversy over Clinton's use of a private server to send emails while secretary of state.

The Washington Post has reported that Trump's team sees getting rid of Sessions as part of a potential strategy to fire Mueller and end the investigation.

Sessions, however, has said he has no plans to resign.

The website Axios reported that Trump was considering replacing Sessions with another early supporter, former New York mayor Rudy Giuliani.

But Giuliani dismissed the report and said Sessions was right to have recused himself from the Russia probe, CNN reported.

On Monday, Trump had already wondered out loud why Sessions was not investigating Clinton.

The White House also alleged last week that the Democrats colluded with Ukraine during the 2016 campaign, adding another twist to the president's counter-offensive.

Trump tweeted early morning on Tuesday:

Kiev's embassy in Washington refuted that claim, saying it didn't help "any candidate" in the election.

Deliberate campaign

Two allies of Sessions said Trump's public attacks went beyond a president simply venting his frustration but were part of a deliberate campaign to encourage the attorney general to step down.

They said Trump was likely reluctant to fire Sessions after his sacking of FBI Director James Comey backfired and led to the appointment of an independent special counsel, Robert Mueller, whose wide-ranging probe into contacts between Trump aides and Russian officials has cast a deep shadow over Trump's presidency.

The Kremlin says it did not interfere in the election, and Trump has denied any collusion.

Asked about Sessions' future, Trump said at a news conference on Tuesday, "Time will tell. Time will tell."