President Donald Trump wants to know "what is taking so long" with an internal Justice Department probe expected to criticize the FBI and its handling of the case involving Democrat Hillary Clinton's private email server.

"What is taking so long with the Inspector General's Report on Crooked Hillary and and Slippery James Comey. Numerous delays. Hope Report is not being changed and made weaker! There are so many horrible things to tell, the public has the right to know," Trump tweeted early Tuesday. "Transparency!"

What is taking so long with the Inspector General’s Report on Crooked Hillary and Slippery James Comey. Numerous delays. Hope Report is not being changed and made weaker! There are so many horrible things to tell, the public has the right to know. Transparency! — Donald J. Trump (@realDonaldTrump) June 5, 2018

The FBI's timing has been a sore point for Clinton supporters, who say then-director James Comey's announcement of the review less than two weeks before the Nov. 8, 2016, election contributed to her loss to Trump.

Last month, the DOJ asked the inspector general, Michael Horowitz, to expand that probe to include a look at whether Trump associates were improperly monitored during the campaign for political reasons.

Trump has repeatedly criticized the FBI's handling of the Russia probe and said the focus should be on the Clinton email case.