Paul Callan is a CNN legal analyst, a former New York homicide prosecutor and currently is counsel at the New York law firm of Edelman & Edelman PC , focusing on wrongful conviction and civil rights cases. Follow him on Twitter @paulcallan . The opinions expressed in this commentary are his own.

(CNN) The Trump administration's soft-spoken, yet hard-edged attorney general, Jeff Sessions, may have just squandered the reputation for integrity that he earned when recusing himself from Russia investigation.

The enigmatic attorney general held to his principled recusal even in the face of repeated presidential insults and abuse. Now he appears to have thrown it all away by, according to a source familiar with the matter, pressuring the FBI to alter its chain of command in a manner that could affect special counsel Robert Mueller's Russia probe.

Sessions' role as an early and active participant in the Trump campaign made his recusal from any supervisory role in the Mueller investigation mandatory. His conflict of interest problems were exacerbated by a claimed memory lapse regarding a previous contact with the Russian ambassador when testifying at his Senate confirmation hearing. He also admitted that during his confirmation proceedings he failed to disclose contact with Russian operatives that he didn't consider relevant

Sessions has now forfeited the credibility and reputation for integrity he earned at such great personal cost -- Trump hammered him repeatedly for his recusal from the Russia matter -- by reportedly pressuring newly appointed FBI Director Christopher Wray to remove the FBI's deputy director, Andrew McCabe.

Sessions may have a legitimate beef regarding some aspects of McCabe's alleged involvement in both the Russia and Hillary email investigations. Attempted tampering with the FBI's chain of command, however, is particularly offensive here in that Sessions himself could theoretically be a target or key witness in the investigation. In fact, he submitted to hours of questioning by Mueller just last week.

Deputy Attorney General Rod Rosenstein should be supervising all aspects of the Russia investigation as needed, not Sessions.

Sessions' complaints undoubtedly relate to McCabe's service in the FBI's #2 spot while the agency conducted the Hillary email investigation. McCabe's wife, a Democrat who ran for political office in Virginia, had previously accepted approximately $700,000 in campaign contributions linked to friends and high-ranking political allies of Hillary Clinton.

The FBI says this is not a violation of law or FBI regulations but it sure looks bad to anyone with a moral compass and a sense of fundamental fairness.

McCabe was also in the chain of command with respect to one of the FBI's top counterintelligence agents, Peter Strozk, who exchanged text messages with FBI lawyer Lisa Page, some of which described Trump as an "idiot," a "d*uche" and opined that his potential election would be "terrifying." Strozk was involved in the Russia investigation, as well as the investigation into Hillary Clinton's email practices.

Sessions' belief that FBI Director Wray should reorganize the FBI's upper management may very well be objectively correct. McCabe's continued role as deputy director creates, at the very least, a serious appearance of impropriety in an investigation which is so important to the nation that it requires the purity of "Caesar's wife."

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Yet a fair investigation requires that the so-called "recused" attorney general should keep his hands off all aspects of the Mueller probe, including the FBI chain of command. The attorney general has a clear ethical obligation to back away from pressuring FBI Director Wray. If he can't do that, perhaps it's time to redeem at least a shred of his honor by resigning the post of attorney general.