Metro

How Corey Johnson is about to hold two of the city’s most influential offices

New York’s next public advocate will have a familiar face — that of City Council Speaker Corey Johnson.

Under the law, Johnson will assume the post when the office’s current occupant, Letitia James, is sworn in as state attorney general on Jan. 1.

As public advocate, Johnson will also be next in line of succession in case anything happens to Mayor Bill de Blasio.

“I put my whole heart into everything I do, and my brief time as Acting Public Advocate will be no exception,” Johnson told The Post. “I plan to take the role and responsibilities of Acting Public Advocate seriously, as New Yorkers deserve nothing less.”

Johnson will keep the office until a special election is held on Feb. 26 to replace James.

Over those two months, the speaker said he will use the new bully-pulpit to focus the spotlight on the crumbling state-run subway system and using 311 data to examine how agencies are responding to New Yorkers’ needs.

As many as two dozen potential candidates are gunning for the position, which has traditionally been used as a springboard to higher office.

The special election will cost taxpayers a bundle.

The Board of Elections said it will spend $15 million to open polls citywide — more than four times the $3.5 million public advocate’s annual budget.

And candidates who can meet minimum fundraising thresholds are eligible for public matching funds, which could add millions to the bill.