Key House chairmen on Sunday made it plain they’re charging ahead on what President Trump calls a “witch hunt” — talking as if they already have proof of impeachable offenses even as they announce they’re going to keep looking for something, anything, that actually fits the bill.

On CBS, Intelligence Committee Chairman Adam Schiff cited “direct evidence” of Team Trump’s collusion with Russia in 2016, yet pointed only to what’s long been in the public record — Donald Trump Jr.’s idiotic response to e-mails from a bozo British publicist and so on.

Hmm: Schiff claimed he’d seen hard proof of collusion back in 2017, yet has never offered more than vapor.

On ABC, House Judiciary chief Jerry Nadler said he’ll demand documents from dozens of Trump associates. Nadler says it’s already “very clear that the president obstructed justice,” yet he’s unsure that means impeachment. Huh?

Look: Special Counsel Robert Mueller has been looking into all of this and more for nearly two years. Any effort to suppress his findings is sure to fail thanks to leaks.

“New” investigations will give Nadler & Co. regular opportunities to posture. But it all boils down to the Keystone Kops’ effort to restage “All the President’s Men.”