Attorney General Bill Barr has gone full anti-President Donald Trump in the weeks since the election and the two are not on friendly terms.

But some of his work that has caused the president to be furious with Barr started before the election took place.

Reports say that Barr knew about the investigation into Hunter Biden and actively worked behind the scenes to stop Americans from knowing the investigation was taking place, The Daily Mail reported.

Bill Barr has known about investigations involving Joe Biden’s son Hunter since at least the spring, according to a report, and did his best to stop the information leaking out before the election.

In news which angered his boss Donald Trump, the attorney general – whose job is already said to be hanging in the balance – acted to stop the investigation being made public, the Wall Street Journal reported.

Justice Department guidelines advise investigators against taking overt actions in a run-up to an election so as not to be seen as affecting the outcome.

The president has railed against Barr on Twitter since it was discovered that Barr hid the investigation that could have changed people’s decision to vote for former Vice President Joe Biden.

“IF Biden gets in, nothing will happen to Hunter or Joe. Barr will do nothing, and the new group of partisan killers coming in will quickly kill it all. Same thing with Durham. We caught them cold, spying, treason & more (the hard part), but ‘Justice’ took too long. Will be DOA!” the president said.

“Why didn’t Bill Barr reveal the truth to the public, before the Election, about Hunter Biden. Joe was lying on the debate stage that nothing was wrong, or going on – Press confirmed. Big disadvantage for Republicans at the polls!” the president said.

And after the two had a contentious meeting last week CNN reported that Barr is not impressed nor frightened of the president.

The report said that Barr has decided to stay on as attorney general until the end of Trump’s presidency unless he believes he is about to be fired.

"Barr cannot be intimidated by Trump. This is the real story. None of this matters -- it's the deposed king ranting. Irrelevant to the course of justice and to Trump's election loss," a source told CNN on Saturday.