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President Donald Trump on Monday railed against the federal probe into Russian interference in the 2016 election, accusing special counsel Robert Mueller's team of having "unrevealed conflicts of interest" and insisting that obstruction of justice is a "made-up phony crime."

"The Russia Witch Hunt is rapidly losing credibility. House Intelligence Committee found No Collusion, Coordination or anything else with Russia. So now the Probe says OK, what else is there? How about Obstruction for a made up, phony crime.There is no O, it’s called Fighting Back," Trump wrote in the first of two Monday morning tweets on the topic. Mueller's team is reportedly probing whether Trump committed obstruction of justice by firing James Comey as FBI director last year.

Trump, referring to Mueller's team, added, "The 13 Angry Democrats in charge of the Russian Witch Hunt are starting to find out that there is a Court System in place that actually protects people from injustice."

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"And just wait 'till the Courts get to see your unrevealed Conflicts of Interest!" Trump said.

The Russia Witch Hunt is rapidly losing credibility. House Intelligence Committee found No Collusion, Coordination or anything else with Russia. So now the Probe says OK, what else is there? How about Obstruction for a made up, phony crime.There is no O, it’s called Fighting Back — Donald J. Trump (@realDonaldTrump) May 7, 2018

The 13 Angry Democrats in charge of the Russian Witch Hunt are starting to find out that there is a Court System in place that actually protects people from injustice...and just wait ‘till the Courts get to see your unrevealed Conflicts of Interest! — Donald J. Trump (@realDonaldTrump) May 7, 2018

It wasn't immediately clear what conflicts of interest Trump was referring to, although the president has repeatedly slammed the Mueller probe as a "witch hunt." Mueller, a Republican, was appointed FBI chief by GOP President George W. Bush in 2001 and served until 2013.

The tweets come just days after a U.S. federal judge, T.S. Ellis, said he is skeptical about Mueller's ability to bring charges against former Trump campaign manager Paul Manafort.

Ellis, a Reagan appointee, hammered the special counsel’s office Friday, suggesting that the charges against Manafort have nothing to do with Russian election interference and that the special counsel is only interested in squeezing Manafort for information "that would reflect on Mr. Trump or lead to his impeachment."

Trump’s tweets, however, could also be part of a more combative legal strategy that the president's newly reshuffled legal team is said to be taking against the Mueller probe.

Last week, Trump tapped Emmet Flood, who advised Bill Clinton during his impeachment proceedings, to assist in the Russia investigation after Ty Cobb, the lead White House attorney handling the probe, announced plans to retire. Former New York Mayor Rudolph Giuliani, a longtime Trump ally and ex-federal prosecutor in New York, also recently joined Trump's legal team to provide advice on how to deal with the special counsel's probe.

Mueller reportedly wants to question Trump in detail about his ties to Russia, the president's firing of Comey and whether he tried to interfere with the investigation, according to a list of questions published by The New York Times last week.

In less than a year — Mueller was appointed special counsel in May 2017 — his team's work has resulted in 19 individuals being charged with crimes. That number includes 13 Russian nationals and five people who pleaded guilty (among them Trump's former national security adviser, Michael Flynn, and Trump campaign adviser George Papadopoulos).