Democrats and the media for three years used a fog of facts and speculation to lull America into forgetting there was never a shred of evidence of Trump-Russia collusion. They flooded the zone with another flurry of scattershot claims in their campaign against Justice Brett Kavanaugh. Republicans might bear these tactics in mind as they confront the left’s new impeachment push.

In the two weeks since the White House released the transcript of President Trump’s call with Ukrainian President Volodymyr Zelensky, the debate has...