Mayor Martin Walsh will be nominated to serve as the Secretary of Labor for the Biden-Harris administration, according to a report from Politico.

The report - which cites sources within the Biden transition team— follows months of speculation that the 53-year-old Boston mayor was a leading candidate for the president-elect's cabinet.

Biden and Walsh have been close allies in recent years. The president-elect presided at Walsh's most recent inauguration.

If Walsh were to accept the post, he will leave a vacancy in the Mayor's office that would, by statute, be filled by City Council President Kim Janey of Roxbury. She would be the first Black person to serve as the city's chief executive.

According to City Clerk Maureen Feeney, if Walsh was to leave his City Hall post before March 2021, a special election would be scheduled. If he leaves after March, the September primary election would be the next window to begin picking a new mayor.

There are already two candidates seeking election to the mayor's job in 2021. City Councillor-at-Large Michelle Wu and District 4 Councillor Andrea Campbell of Mattapan. Dorchester resident Annissa Essaibi-George, also a citywide councillor, is considering a run herself if Walsh is not in the race.

Councillor Wu offered a swift response congratulating Walsh— who has not yet commented on the report.

"Congratulations to Mayor Marty Walsh on his nomination as Labor Secretary for the Biden Administration," said Wu. "He will be the first union member to serve in this role in nearly 50 years, and his leadership will come at a critical time for the labor movement. There is much work to do to clean up the backwards, anti-worker policies of the Trump administration that have hurt so many here in our city, and Boston needs a partner to fight for working families at the federal level."

Sen. Ed Markey tweeted: "Fantastic news. As a union leader, [Walsh] will bring the commitment to workers and working families that is desperately needed right now. His tremendous leadership in Boston on climate action, health care, and social action make him ready on day 1."