U.S. President Donald Trump and Lebanese Prime Minister Saad al-Hariri (not pictured) attend a joint press conference in the Rose Garden of the White House in Washington, U.S. Thomson Reuters

President Donald Trump ratcheted up his criticism of Attorney General Jeff Sessions during an interview with the Wall Street Journal on Tuesday.

Trump said he was "disappointed" in Sessions and added that the former senator endorsed him because Trump's rallies drew large crowds, and not because of loyalty.

"I had 40,000 people," Trump said of his campaign rallies. "He was a senator from Alabama ... he looks at 40,000 people and he probably says, 'What do I have to lose?' And he endorsed me," Trump said.

"So it's not like a great loyal thing about the endorsement. But I'm very disappointed in Jeff Sessions," he added.

Trump reiterated his disappointment in Sessions during a joint press conference Tuesday with Lebanese Prime Minister Saad Hariri and said "time will tell" whether or not he will fire Sessions.

Trump soured on Sessions after the attorney general recused himself in March from any current or future Department of Justice investigations into the Trump campaign and Russia's interference in the 2016 election.

"He should not have recused himself almost immediately after he took office," Trump said during the press conference Tuesday. "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 said, adding that he believed Sessions' recusal was "unfair to the presidency."

When he was asked how long he would continue publicly criticizing Sessions while keeping him on as attorney general, Trump told the Journal, "I'll just see. It's a very important thing."

Sessions said last week that he would remain in his position as long as it was appropriate.

Trump has consistently leveled criticism towards ongoing FBI and congressional investigations into whether his campaign colluded with Russia to tilt the 2016 election in his favor, frequently calling the probes a "witch hunt" led by Democrats he said were upset by their election loss.

Trump also publicly warned special counsel Robert Mueller, who is spearheading the FBI's Russia investigation, last week against investigating the Trump family's finances, saying that Mueller would be crossing a line if he did so.

"Look, this is about Russia," Trump said. "So I think if he wants to go, my finances are extremely good, my company is an unbelievably successful company."

Trump's comments came the day before a Bloomberg report that said Mueller had expanded his probe to look at Trump's past business dealings.

Some have speculated that Trump's public attacks on Sessions, his own Cabinet member, may indicate he's setting the stage to appoint someone who will fire Mueller. On Monday, Axios reported that Trump was weighing replacing Sessions with Rudy Giliani, an avid Trump supporter and early campaign surrogate.

Giuliani denied the report on Monday and said that Sessions made the right decision when he recused himself from any current or future investigations into the Trump campaign.