"NBC Nightly News" anchor Lester Holt will moderate the first presidential debate Monday. (Photo by Jose Luis Villegas/the Sacramento Bee via AP)

Lester Holt, anchor of "NBC Nightly News" will moderate Monday's presidential debate between Hillary Clinton and Donald Trump. Previous moderators have advised this year's questioners to be as invisible as possible, but scrutiny is inevitable.

Before the lights go on, here are five things to know about Holt:

Holt is a registered Republican

Donald Trump has spent the weeks leading up to the general election debates predicting unfair treatment by the moderators. He says the media using criticism of Matt Lauer's performance during a candidates forum this month to pressure the moderators into attack mode.

"They're hitting Matt Lauer, and that's sort of indicative of what they're — they're trying to game the system," Trump told Fox News last weekend. "They want — and this, I think, is terrible — they want the hosts to go after Trump. And that's what they're doing by gaming the system."

Conspiratorial as Trump's theory is, it can't be disproven. But the shot he took at Holt can be.

"Lester is a Democrat," Trump told Bill O'Reilly last week. "It’s a phony system. They are all Democrats. It’s a very unfair system."

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 was September 26. (Sarah Parnass/The Washington Post)

Time magazine checked the voter rolls in New York, and it turns out Holt is actually a registered Republican. Trump still might find things to complain about Monday night, but a case for partisan bias against him will be tough to make.

Holt is the first black presidential debate moderator since 1992

Holt, whose grandparents immigrated to the United Stats from Jamaica, is the first black moderator of a general election presidential debate since Carole Simpson in 1992. Gwen Ifill moderated vice-presidential debates in 2004 and 2008, and Bernard Shaw moderated the VP debate in 2000, but it has been 24 years since a black journalist moderated a debate between the major-party nominees for president.

Holt, whom NBC declined to make available for interviews before the debate, does not talk about his race often. He did say this to the Chicago Tribune in 1995, when the paper profiled the then-anchor of WBBM-TV's nightly newscast: "Everyone knows I'm black. I am who I am. This is the person that Lester Sr. and June Holt raised, and I make no apology for it. At the same time, I'm never going to pull a race card to get what I want. You can't have it both ways."

Dominic Carter, a fellow black TV journalist who moderated one of Hillary Clinton's Senate campaign debates in 2006, said Holt's selection is significant, but viewers should not expect his background to influence his questioning.

"We are journalists first," Carter said. "That's a huge distinction. We're not there to advocate on issues relating to African Americans. We're there advocating and asking questions on behalf of the American people. You don't want people to put you in the box of the black guy doing the debate. So you have to be over and above in terms of fairness and professionalism."

He's not really into the Twitter

Holt, 57, has not tweeted in almost a month. He was fairly active while in Rio de Janeiro during NBC's coverage of the Olympics, sharing images like these:

In general, however, it is not unusual for Holt to go several days or even a week between tweets. His relative disinterest in social media stands in contrast to Trump's obsession.

He moderated a Democratic primary debate

Holt got to practice his moderating skills at a Democratic debate in January, though he split questioning duties that night with Andrea Mitchell.

He was not involved in any major clashes during the debate but showed a willingness to ask tough questions, such as when he asked Clinton about the "reset button" with Russia during her tenure as secretary of state.

"Secretary Clinton, you famously handed Russia's foreign minister a reset button in 2009," Holt said. "Since then, Russia has annexed Crimea, fomented a war in Ukraine, provided weapons that downed an airliner and launched operations, as we just did discuss, to support Assad in Syria. As president, would you hand Vladimir Putin a reset button?"

Holt has two honorary doctorates, but no bachelor's degree

Apparently the secret to becoming a big-time political anchor is not graduating from college. "Meet the Press" anchor Chuck Todd never finished his studies at George Washington University. (He told me he plans to do so before his kids go to college.) The late ABC anchor Peter Jennings never even went to college, dropping out of high school.

Holt left California State University-Sacramento after two years to work at a radio station in San Francisco. The Sacramento Bee told the story last year:

Lester Holt Sr. was concerned in 1979 when he learned that his son was planning to drop out of California State University, Sacramento, to work at a San Francisco radio station. But he wasn’t as worried as his wife, June.

“She predicted poverty and failure,” he said with a laugh.

But the Rancho Cordova couple gave their blessing, firm in the belief that Lester Jr. would go far with hard work, talent and a likeable personality in his chosen field of broadcast journalism.

Things worked out okay. Since dropping out, Holt has received honorary doctorates from Cal State Sacramento and Pepperdine University.