RussiaGate is now a complete dead letter — but ObamaGate is taking its place. Just how far did the then-president go to cripple his successor?

It's now clear the Obama-Comey FBI and Justice Department never had anything more substantial than the laughable fiction of the Steele dossier to justify the "counterintelligence" investigation of the Trump campaign. Yet incessant leaks from that supposedly confidential probe wound up consuming the Trump administration's first months in office — followed by the Bob Mueller-led special counsel investigation that proved nearly the "total witch hunt" that President Trump dubbed it.

Information released as the Justice Department dropped its charges against Gen. Mike Flynn shows that President Barack Obama, in his final days in office, played a key role in fanning the flames of phony scandal. Fully briefed on the "Crossfire Hurricane" investigation, he knew the FBI had come up with nothing despite months of work starting in July 2016.

Yet on Jan. 5, 2017, Obama told top officials who'd be staying on in the new administration to keep the crucial facts from Team Trump.

It happened at an Oval Office meeting with Vice President Joe Biden, intel chiefs John Brennan and Jim Clapper and national security adviser Susan Rice, as well as FBI Director Jim Comey and Deputy Attorney General Sally Yates.

"From a national-security perspective," Rice's memo afterward put it, "President Obama said he wants to be sure that, as we engage with the incoming team, we are mindful to ascertain if there is any reason that we cannot share information fully as it relates to Russia."

This even as then-President Obama also directed that as many people as possible across his administration be briefed on the (utterly unsubstantiated) allegations against Team Trump — and as Rice and others took unprecedented steps to "unmask" US citizens like Flynn whose conversations had been caught on federal wiretaps of foreigners.

Indeed, the Obama administration went on a full-scale leak offensive — handing the Washington Post, New York Times and others a nonstop torrent of "anonymous" allegations of Trumpite ties to Moscow. It suggested that the investigations were finding a ton of treasonous dirt on Team Trump — when in fact the investigators had come up dry.

Sadly, Comey's FBI played along — sandbagging Flynn with the "friendly" interview that later became the pretext for the bogus charges dropped last week, as well as triggering the White House chaos that led to his ouster. This when the FBI had already gone over the general with a fine-tooth comb, and concluded that, no, he'd done nothing like collude with the Russians.

Meanwhile, Comey himself gave Trump an intentionally misleading briefing on the Steele dossier. That was followed by leaks that suggested the dossier was the tip of an iceberg, rather than a pack of innuendo that hadn't at all checked out under FBI scrutiny.

Pulitzer Prizes were won for blaring utter fiction; the Trump administration was kneecapped out of the gate. Innocents like Flynn were bankrupted along the way.

Say this about Obama: He knows how to play dirty.

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Meanwhile, the Justice Department does not intend to release the list of officials who requested unmaskings of the Trump campaign and administration officials and deferred to the ODNI for any further comment.

In addition, the department has been reviewing unmasking as part of U.S. attorney John Durham's broader review of the activities of investigators in 2016 and 2017 during the Russia probe.

Critics, including nearly 2,000 former DOJ officials, have argued the move was part of a pattern of Barr looking to undermine an investigation that was politically damaging for President Donald Trump. They want Barr to resign over his intervention in the case.

Susan Rice has admitted to "unmasking" names within intelligence reports to give her context for how they pertain to the overall briefing material in the President's Daily Briefing. With dozens of people with access to President Obama's PDB, Rice's unmasking of the intelligence report names gave dozens of people direct access to unmasked intelligence - including Obama officials who could, perhaps did, use the PDB for specific and intentional political purposes.