Sixteen assistant U.S. attorneys specially assigned to monitor malfeasance in the 2020 election urged Attorney General William P. Barr on Friday to rescind his recent memorandum allowing investigators to publicly pursue allegations of “vote tabulation irregularities” in certain cases before results are certified, saying they had not seen evidence of any substantial anomalies.

In a letter — an image of which was shown to The Washington Post — the assistant U.S. attorneys told Barr that the release of his Monday memorandum — which changed long-standing Justice Department policy on the steps prosecutors can take before the results of an election are certified — “thrusts career prosecutors into partisan politics.”

The signers wrote that in the places where they served as district election officers, taking in reports of possible election-related crimes, there was no evidence of the kind of fraud that Barr’s memo had highlighted. Barr’s memo authorized prosecutors “to pursue substantial allegations of voting and vote tabulation irregularities prior to the certification of elections in your jurisdictions in certain cases,” particularly where the outcome of an election could be affected.

“The policy change was not based in fact,” the assistant U.S. attorneys wrote.

The letter was signed by assistant U.S. attorneys in 15 different federal court districts: Western Pennsylvania, Western North Carolina, New Mexico, Maryland, Southern Ohio, Eastern Kentucky, Southern Iowa, Western Arkansas, Southern New York, Eastern New York, Oregon, Kansas, Northern California, the Virgin Islands and the Northern Mariana Islands. Two signers were from Oregon.

Asked for comment on the assistant U.S. attorneys’ assertions, Kerri Kupec, a Justice Department spokeswoman, said, “Perhaps they did not read the memo.” She pointed to a section in which Barr urged caution, noting, “Nothing here should be taken as any indication that the Department has concluded that voting irregularities have impacted the outcome of any election.

“While it is imperative that credible allegations be addressed in a timely and effective manner, it is equally imperative that Department personnel exercise appropriate caution and maintain the Department’s absolute commitment to fairness, neutrality and non-partisanship,” the section read. “You are the most senior leaders in the United States Department of Justice and I trust you to exercise great care and judgment in addressing allegations of voting and vote tabulation irregularities. While serious allegations should be handled with great care, specious, speculative, fanciful or far-fetched claims should not be a basis for initiating federal inquiries.”

Current and former Justice Department officials have in recent days told The Washington Post they were stunned and frustrated by Barr’s election-related directive, as they worried Barr was aiding President Trump’s effort to cast doubt on his defeat.

Some weeks ago, when Barr had first proposed the move, officials in the criminal division — including political leadership — had pushed back vigorously and thought they had dissuaded the attorney general from taking such a step, only to be blindsided when the memo hit their inboxes Monday. The head of the department’s election-crimes branch, Richard Pilger, told colleagues within hours that he was stepping down from that job and taking a lesser position at the department, citing the new guidance.

The district election officers wrote, “We disagree with the Memorandum’s argument that the impact of taking overt investigative and prosecutorial actions on the outcome of an election is greatly minimized after voting ends but before certification occurs.”

Critics have said Trump could now point to the memo itself to aid his unfounded claims of massive voter fraud, and perhaps U.S. attorneys across the country would feel empowered to hold news conferences or take other public steps that would suggest massive fraud, even if it was far from proven. Barr noted in the memo that he had already greenlighted investigative steps “in specific instances,” but did not detail what those were, and Justice Department officials said it was unclear to what he was referring.

Others have said the memo was so heavily caveated that it was unlikely to have a real impact. On Friday, 23 Democratic state attorneys general — including those in Michigan, Wisconsin and Nevada, where Trump has pursued or threatened legal challenges — also sent a letter to Barr complaining about the policy change and noting that “so far, no plausible allegations of widespread misconduct have arisen that would either impact the outcome in any state or warrant a change in DOJ policy.”

Correction: An earlier version of this article said a letter from Democratic attorneys general was signed by the Pennsylvania attorney general. He was not among the signers.