Thursday's news that President-elect Joe Biden will tap Boston Mayor Marty Walsh for labor secretary took many pundits by surprise, as Walsh has been fundraising for another mayoral run and Biden faces calls to diversify his cabinet. But WBZ-TV Political Analyst Jon Keller said he thinks the news makes sense.

“They’re old pals, they have similar backgrounds — difficult childhoods marked by challenges, Biden [had] a severe stutter, Walsh [and] his battle with childhood cancer," Keller told GBH Morning Edition Host Joe Mathieu Friday. "They went on to become successful adults with similar styles: schmoozers, dealmakers. Walsh is taking on a big job, and I think Biden wanted somebody in there that he really was simpatico with and knew he could trust.”

If Walsh is confirmed, his departure for Washington would clear the way for a potentially large and diverse field of mayoral candidates this November.

In accordance with city rules, Kim Janey — currently Boston City Council president — would assume the role of acting mayor, becoming the first woman and person of color to lead the city. According to Keller, this could well position her for a potential election victory in November, should she decide to run. Janey has not announced that she is entering the 2021 mayoral race.

It's happened before. Keller recalled 1993, when President Bill Clinton appointed Boston Mayor Ray Flynn ambassador to the Vatican. Tom Menino, a little-known councilor from Hyde Park, became acting mayor. He went on to win the election in the fall and became the city's longest-serving mayor.

“You wonder about history repeating itself,” Keller said. “I don't think very many Bostonians outside of her district know very much about Kim Janey. I think once they get to know her, they're going to like her.”

Watch: Keller on Janey being his early frontrunner for mayor

Two candidates — city councilors Michelle Wu and Andrea Campbell — have already officially jumped into the mayoral race. But, Keller said, the field could grow significantly in the coming months. He said he's keeping an eye on city councilors Annissa Essaibi-George, Michael Flaherty, and Matt O’Malley, state senators Mike Rush, Nick Collins and Sonia Chang-Díaz, Sheriff Steve Tompkins, and State Representative Nika Elugardo.

As for Walsh, Keller said he expects his confirmation as labor secretary to be a breeze, especially after the upset in Georgia that gave Democrats control of the Senate.

“They’re going to be hard-pressed to find traction against Marty Walsh,” Keller said. “I think it’s a slam dunk.”