Josh Campbell is a CNN law enforcement analyst. He previously served as a supervisory special agent with the FBI, special assistant to the bureau's director, and is currently writing a book on recent attempts by elected officials to undermine the rule of law. Follow him on Twitter at @joshscampbell. The views expressed in this commentary are his own. View more opinion articles at CNN.

(CNN) Friday, September 7 marks the 60-day point before voters go to the polls in what is shaping up to be one of the most consequential midterm elections in recent memory.

While it may seem arbitrary to some, the date in the calendar is a significant one, because it marks the beginning of a window of time during which federal prosecutors and FBI agents typically refrain from taking any overt investigative steps on cases that might impact or influence an election. It's like crossing a line that means "after this, no sudden moves until the election is done."

Special counsel Robert Mueller and his team investigating the Trump campaign's alleged ties to Russia should adhere to this Justice Department custom and cease any public comments or significant disclosures until after the election. As the nation's chief executive who oversees the Justice Department, President Donald Trump should do the same, as unlikely as that sounds.

With all the norms Trump has trampled in his 19 months in office, why should we care if he violates this one? Because, importantly, the power of his office and the presidential bully pulpit at his disposal mean his statements and actions have a greater ability to influence the public than the officials at DOJ who work for him -- or, arguably, any members of the Mueller team investigating him.

JUST WATCHED Trump attacks Sessions for indicting two Republican Reps Replay More Videos ... MUST WATCH Trump attacks Sessions for indicting two Republican Reps 04:34

Although Trump sees the world through the singular lens of what impacts him personally, he must remember that his role as commander in chief means he is the de facto head of the Justice Department and every other agency in the executive branch. If Mueller is now going to go quiet, Trump should follow his lead.

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