Federal prosecutors are at risk of an "enormously compromising" situation if they continue to pursue cases against Donald Trump's perceived enemies, according to a group of former presidential ethics counsel.

Norman Eisen, co-founder and a board member of Democracy Defenders Action, and Richard W. Painter, law professor at the University of Minnesota and Virginia Canter, chief counsel for ethics and anti-corruption of Democracy Defenders Fund, wrote a piece Sunday called, "If the Trump DOJ can indict Comey, then no one is safe from political prosecution."

"In the United States, a president should never order prosecutions of his enemies. As the former ethics counsels for Presidents George W. Bush, Barack Obama and Bill Clinton, we never once saw them or anyone working for them suggest that the Department of Justice should prosecute a specific person, much less a political adversary," the pair wrote. "Under all three presidents, the White House policy was not to comment on a Department of Justice indictment; the president in particular did not comment either — before or after. The Justice Department made prosecutorial decisions independent of the White House."

Eisen and Painter go on to call for an investigation.

"We have written the chairs and ranking members of the Senate and House Judiciary committees, as well as the DOJ’s inspector general and counsel for the office of professional responsibility. In those letters (on which this essay is based) we urgently request an investigation into possible prosecutorial abuses and ethics violations by Lindsey Halligan, the newly appointed interim U.S. attorney for the Eastern District of Virginia, in connection with her having improperly brought charges against Comey," the piece states.

They go even further, alleging that the "Comey matter is rife with procedural improprieties that are prejudicial to Comey’s right to a fair trial, regardless of the substance of any charge."

"It is not proper to comment on what’s going on in a grand jury, it’s not proper to impugn an uncharged person, and it’s certainly not appropriate for a president to say that a subject is 'guilty as hell,' as Trump did of Comey last week, and then for the president to seek to fire a prosecutor who refuses to prosecute him and substitute a replacement who will," they wrote Sunday. "Indeed, a criminal case against Comey could be a nightmare for any prosecutor on both vindictive and selective prosecution grounds and on the merits. The discovery that the judge will likely order here alone will be enormously compromising in a variety of ways."

They caution Trump's DOJ with one final warning:

"If federal prosecutors do not want to go down this road, they should spend their time, and taxpayer money, prosecuting real criminals, not the president’s political enemies. Instead, the Justice Department is still reportedly looking at charging Letitia James and is also said to be investigating Fulton County, Georgia, District Attorney Fani Willis, not to mention Sen. Adam Schiff, former CIA Director John Brennan, former national security adviser John Bolton and many others."

Read the report here.