Political appointees at the U.S. Justice department will be barred from attending campaign events or fundraisers, according to new guidance issued by U.S. Attorney General Merrick Garland on Tuesday ahead of November's midterm elections.

"I know you agree it is critical that we hold ourselves to the highest ethical standards to avoid even the appearance of political influence as we carry out the Department's mission," Garland wrote in his memo.

"It is in that spirit that I have added these new restrictions on political activities by non-career employees."

While it is common for the Justice Department to remind its staff to tread carefully about political activities ahead of election seasons, Garland's memo contains among the most restrictive policies in recent times.

Federal employees in general are subject to the Hatch Act, a law which limits some of their political activities to ensure the government is free from partisan influence.

Previously, political appointees at the department were permitted to attend partisan events in their personal capacity, as long as they sought prior approval. Under the new guidance, however, there will be no exceptions - including on the evening of Election Day itself.

The change comes at a time when the Justice Department is under a national microscope over its extraordinary decision to search the Florida estate of former Republican President Donald Trump earlier this month as part of an ongoing criminal investigation into whether he illegally retained government records, including some marked as top secret.

Trump has accused the FBI of a partisan witch-hunt, and his rhetoric led one of his supporters to attack an FBI field office in Ohio earlier this month before later dying in a shoot-out with police.

The Justice Department responded to Trump's political attacks by publishing the search warrant and a redacted copy of the affidavit outlining its evidence.

The documents show Trump retained highly classified records at his home in Mar-a-Lago after leaving office in January 2021, some of which involve the country's most closely-held secrets about confidential human sources and intelligence gathering.

The FBI located more sets of classified records during its Aug. 8 search.

In addition to the pressure the department has faced over its investigation into Trump, some of its political appointees have also faced criticism for attending political functions.

Republican Senator Tom Cotton of Arkansas in July called for an investigation after Rachael Rollins, an outspoken progressive prosecutor who serves as the U.S. Attorney for Massachusetts, attended a Democratic fundraiser that month that was also attended by First Lady Jill Biden.

Rollins in a tweet following news reports on her attendance said she had "approval to meet Dr. Biden & left early to speak at 2 community events."

A spokesperson for Rollins did not immediately respond to a request for comment on Tuesday.