An informal adviser has sent President Trump a memo arguing that his complaints about the fairness of moderators at the 2020 debates is “fully justified.”

Doug Wead, a conservative commentator who has interviewed the president, told Trump that nearly all the past moderators can be described as leaning to the left.

The research by Wead, who worked in George H.W. Bush’s White House, is a mixed bag. In some cases, the memo points to past comments or episodes that could concern a Republican candidate. In other cases, it merely links to critiques from conservative outlets or ephemeral citations that unnamed friends believe the person is left-leaning. And in still others, the evidence provided actually shows their fairness in debates.

TRUMP WORKS THE REFS, HITS THE MEDIA, CASTS DOUBT ON DEBATES

The Wead effort raises the philosophical question of whether journalists can separate personal opinions that might fall to the liberal side from the performance of their jobs, especially on a presidential debate stage.

Trump, who the New York Times says may skip the debates out of concern about the moderators, recently tweeted an attack on the Commission on Presidential Debates, which has staged every general-election debate since 1988. The president said the panel is “stacked with Trump Haters & Never Trumpers,” and that he might seek a different venue to avoid “the nasty politics of this very biased commission.”

The commission, which generally has Republican and Democratic co-chairs, said “our record is one of fairness, balance and non-partisanship.”

The Wead memo says, for instance, that CNN’s Anderson Cooper, a co-moderator in 2016, has launched “vitriolic” attacks on conservatives, citing one comment about Sarah Huckabee Sanders going from “stonewalling all the way to lying.”

The memo rightly calls Bill Moyers, a 1980 moderator, a “proud liberal Democrat.” Moyers was a White House aide to Lyndon Johnson.

As the memo notes, former CNN anchor Candy Crowley took heat during a 2012 debate by interrupting Mitt Romney to side with Barack Obama in a semantic dispute over what the 44th president said after the Benghazi attack.

SUBSCRIBE TO HOWIE'S MEDIA BUZZMETER PODCAST, A RIFF OF THE DAY'S HOTTEST STORIES

But Wead also finds reason to criticize journalists widely viewed as fair, such as Jim Lehrer, who served as a moderator 12 times. He cites conservative criticism of former ABC anchor Charlie Gibson, even while admitting that in 2004 “his handling of the debate between George W. Bush and John Kerry won praise for having a balance between liberal and conservative questions.”

Trump accused NBC anchor Lester Holt, a 2016 moderator, of being a Democrat, but the memo links to a Hollywood Reporter story saying he’d been a registered Republican since 2003 and “earned positive reviews from both sides of the political spectrum” for moderating a Democratic primary debate in the last campaign.

Former CNN anchor Bernard Shaw, a 1988 moderator, is described as leaning left but also quoted as saying “my personal opinions have no place in my work.” Shaw single-handedly devastated Michael Dukakis’ candidacy that year with a question on whether he’d still oppose capital punishment if his wife was raped and murdered.

The memo notes that former ABC anchor Carole Simpson, a 1992 moderator, endorsed Hillary Clinton in 2007. But by that time she was a college instructor, not a working journalist, although Simpson admitted she had “made a mistake.”

Wead praised Fox News anchor Chris Wallace, a 2016 moderator, saying “his reporting and comments show him to be an equal opportunity offender…feared by both Democrats and Republicans.” The memo noted Wallace’s explanation that he is a registered Democrat so his vote will matter in D.C. elections.

In the end, Wead concludes that 23 of the past moderators are “likely liberals” and two are “unknown.”

He told Trump that “he should be able to establish rules that are fair and equal. His team should be able to select at least half of the moderators themselves.” The debate commission was created to take the campaigns out of the business of selecting moderators.

While Wead may well reinforce the president’s suspicions of media moderators, his research shows that such matters can be complicated-- with some bias, to be sure, but some of those suspected of liberal tendencies proving themselves fair on the debate stage.