On Wednesday, just before NBC announced it was suspending Brian Williams from its nightly news broadcast, Lester Holt was told he would be sitting in the anchor chair for the next six months.

Along with doing perhaps the biggest job in television news, under added scrutiny, Holt will also continue to helm the weekend edition of "NBC Nightly News" and host "Dateline," reminding some that he was once nicknamed Iron Pants for his willingness to work seemingly nonstop.

Several television executives said this week that they did not expect Williams to return to the anchor chair, even when his suspension is up. So Holt’s fill-in role could even double as a very public tryout.

If Holt — who will not hold the title managing editor, as Williams did — can keep NBC ahead of its rivals, both in viewer numbers and in advertising dollars, he could hold on to a fiercely coveted position and become the first black anchor with his name on "Nightly News." Nice guys, he has told some, can finish first.

"He’s a total pro, pleasant, unflappable, intelligent," said David Frei, who hosted the Westminster Dog Show with Holt for three years in the mid-2000s. "I’m rooting for him to get the job, and I know a lot of other people are, too."

It will not be easy. In the last week, representatives of prominent people in the news business have been contacting leaders at NBC News about potential candidates to replace Williams — both inside and outside NBC, people with knowledge of the discussions said. Millions of advertising dollars are dependent on the decision. "Nightly News" generates about $200 million a year in advertising revenue, according to Kantar Media.

Though Holt made multiple cameo appearances on the NBC comedy "30 Rock" and played bass with The Roots on "The Tonight Show," he is not a regular on the entertainment circuit or viewed as a crossover star, as Williams was. He views himself, said those close to him at NBC’s 30 Rockefeller Center headquarters, more as a journalistic Swiss army knife, willing and able to take any assignment. He has been such an adept fill-in for Williams in the past that the satirical newspaper The Onion once ran an article suggesting that he adroitly dines with Williams’ family when Williams is away.

Holt, 55, started on television when he was 22. His career began with a series of local news jobs across the country — in Sacramento, Los Angeles, San Francisco, New York and Chicago — before he arrived at MSNBC in 2000, just in time to cover a number of major stories including the Bush-Gore recount, the Sept. 11 terrorist attacks and the invasions of Afghanistan and Iraq. He began to work at NBC in 2003.

Holt, the son of an Air Force technician, likes to tell stories of his time as a DJ on a country and western station in California, where he grew up, with a brief stint in Alaska. He later zoomed around Sacramento in a Jeep Cherokee equipped with a two-way radio and a police scanner to report on shootings and car crashes.

In Chicago, where he worked as an anchor from 1986 until 2000, Robert Feder, a local media commentator, said "he was smooth, competent and professional in every way, just as he appears today." He was also, Feder said, "a solid and well-respected reporter."

Holt used a publicist to promote himself while in Chicago, Feder said, a move that belied his modest image. Feder said he was sent a package in 1999 that included a news release titled "Lester Holt Facts," which had 18 bullet points detailing Holt’s awards and achievements. The package also included a T-shirt bearing a likeness of Holt and the words: "Thanks for Making Me Your Choice for News! Lester."

NBC executives are likely to be swayed more by raw data. In August 2013, Holt was in the anchor chair at "Nightly News" when Williams was out for knee surgery. NBC continued to lead in the ratings race for the broadcast against rivals ABC and CBS, but the network’s edge was tighter, according to Nielsen data provided by Horizon Media. In July that year, NBC led with 7.6 million viewers to ABC’s 7 million. In August, when Holt anchored the broadcast, NBC had 7.3 million viewers to ABC’s 7.1 million.

Though anchors from other networks are tied up in long-term contracts, NBC has a talented bench it can draw from if Holt cannot sustain the more than 9 million viewers Williams commanded before he left.

Other possibilities include Savannah Guthrie, a co-anchor at NBC’s "Today" show and the chief legal correspondent for NBC News. Television industry executives said that not only would Guthrie have the reporting experience — she has been a White House correspondent — but appointing her to the new role also could give NBC the opportunity to make some changes in the roster at the "Today" show, which trails ABC’s "Good Morning America." The names of other "Today" show journalists also have been discussed, including Matt Lauer, Natalie Morales and Willie Geist.

But Holt, said those who know him, has built a career on being ready to walk through whichever doors opened for him. In 2013, as he celebrated a decade of appearances on the "Today" show, Morales said on Twitter that she valued Holt because he was "the calm after the storm. The voice of reason in chaos."

Ravi Somaiya, New York Times