Crossfire’s progenitors thus ignored an obvious question: If Russia promised unspecified dirt on Mrs. Clinton but never delivered it, how would that amount to collusion with the Trump campaign? If anything, such behavior suggests an attempt to entice and potentially embarrass Mr. Trump by dangling the prospect of compromising information and getting his aides to jump at it.

Given the paucity of evidence, it’s staggering that the FBI would initiate a counterintelligence investigation, led by politically biased staff, amid a presidential campaign. The aggressive methods and subsequent leaking only strengthen that conclusion. If the FBI sincerely believed Trump associates were Russian targets or agents, the proper response would have been to inform Mr. Trump so that he could protect his campaign and the country.

Mr. Trump’s critics argue that the claim of political bias is belied by the fact that Crossfire was not leaked before the election. In fact, there were vigorous, successful pre-election efforts to publicize the Trump-Russia collusion narrative. Shortly after Crossfire’s launch, CIA Director John Brennan and Mr. Comey briefed Congress, triggering predictable leaking. Christopher Steele and his patrons embarked on a media roadshow, making their dossier something of an open secret in Washington.