

Hillary Clinton committed weeks ago to the general-election presidential debates. Donald Trump has yet to officially sign on.

One reason for the holdout: "I'll have to see who the moderators are," the Republican nominee told Time magazine last month. "Yeah, I would say that certain moderators would be unacceptable, absolutely."

As of Friday, the lineup was out: NBC's Lester Holt will moderate the first debate Sept. 26 at Hofstra University in Hempstead, New York; ABC's Martha Raddatz and CNN's Anderson Cooper will lead a town-hall-style forum at Washington University in St. Louis on Oct. 9; and Fox News Channel's Chris Wallace will handle the questioning at the final debate Oct. 19 at the University of Nevada in Las Vegas.

So, are these journalists acceptable? Will Trump debate?

The business executive's campaign did not respond to an inquiry. Recall that Trump boycotted a primary debate because he was unhappy with the inclusion of Fox News host Megyn Kelly as a moderator. The stakes were lower then, but he has proven that he will not show if sufficiently miffed.

Beyond his concerns about the moderators, Trump has complained about the schedule; two debates conflict with prime-time National Football League games.

Absent a clear answer from Trump, let's examine his rapport with each of the moderators selected by the Commission on Presidential Debates - a notable roster that includes:

- The first African-American moderator (Holt) since Carole Simpson in 1992 (Gwen Ifill moderated vice-presidential debates in 2004 and 2008, and Bernard Shaw moderated the VP debate in 2000)

- The first openly gay moderator (Cooper)

- And the first moderator from Fox News (Wallace)

Vice-presidential debate moderator Elaine Quijano also represents a couple of milestones. She is the first Asian-American moderator of a general-election debate and the first to work primarily for a digital network (CBSN).

Trump probably has no objection to Wallace, given that he twice agreed to participate in GOP primary debates moderated by the "Fox News Sunday" anchor. But Wallace was tough on the billionaire at those events, most memorably when he used full-screen graphics to fact-check Trump on the spot.

Wallace later told me this: "Do I take a certain pleasure when I open the gate and he decides to walk down the path and I've got the bear trap at the end of the path? Yeah. Sure."

Trump is famously unpredictable. It is conceivable that he could decide not to risk walking into any more Wallace-laid bear traps.

Holt, who moderated a Democratic primary debate, has likewise tripped up Trump with fact-checks. In a June interview, he pressed for evidence to support Trump's claim that Clinton was asleep at critical times during the 2012 attack on a U.S. diplomatic compound in Benghazi, Libya, and got the casino magnate to admit that his assertion might not be true.

"She was asleep at the wheel, whether she was sleeping or not," Trump conceded. "Who knows if she was sleeping?"

Later in the interview, Holt flummoxed Trump by asking how he could say for certain that Clinton's private email server was hacked.

HOLT: But is there any evidence it was hacked other than routine phishing?

TRUMP: I think I read that, and I heard it, and somebody also gave me that information.

HOLT: Where?

TRUMP: I will report back to you. I will give it to you.

HOLT: You said it with such certainty yesterday.

TRUMP: I don't know if certainty. Probably she was hacked.

Trump may not be willing to sign on to a debate moderated by a journalist with a record of throwing him off balance.

Trump participated in a primary debate moderated by Raddatz but faced only a few questions from her: Raddatz split duties with ABC's David Muir, and there were seven candidates onstage. The exchanges were uneventful.

But Raddatz absolutely grilled Trump last summer in his first interview after saying Sen. John McCain, R-Ariz., is "not a war hero." She also confronted Trump about his rhetoric, in general.

"There seems to be a pattern, Mr. Trump," Raddatz said. "When you're criticized or attacked, you often respond with name-calling, using terms like 'dummy,' 'loser,' 'total losers' on Twitter and elsewhere. You even demean some people's physical appearance. Is that something you would continue doing if you were president? Isn't that language beneath the office of the president?"

Trump has granted many interviews to Raddatz's partner in the second debate, Cooper, who moderated two Democratic primary debates. When the GOP standard-bearer finally agreed to appear on CNN recently for the first time in more than two months, it was on Cooper's program.

But that interview produced more headlines about Trump's immigration flip-flops, as Cooper pressed him to reconcile the "softening" he had described to Sean Hannity with the hard-line stance he took early in the campaign. At one point in the conversation, Trump accused Cooper of being on Clinton's side.

"I know you want to protect her as much as you possibly can," said Trump, who often refers to CNN as the Clinton News Network.

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Video: These are the people who will be lobbing questions at Republican Donald Trump and Democrat Hillary Clinton when they go head-to-head at the 2016 presidential debates. The first debate is slated for September 26. (By Sarah Parnass / The Washington Post)