Public Advocate Jumaane Williams wasn’t expecting much resistance in his bid for reelection this year. Then along came Jenifer Rajkumar.

The Queens Assemblywoman abandoned her primary run for city comptroller in January, opting instead to challenge Williams.

Now, he’s being forced to spend his energy and resources on the race, including a $250,000 ad buy this week.

“You know, it was a bit of a surprise,” Williams said in an interview Thursday.

The new ad seems to be a sly dig at Rajkumar, who’s become well known in the political world for standing alongside Mayor Eric Adams at public events.

“I’ll always stand with the people,” Williams says in the ad, also referencing the need for a public advocate who will “stand up, not just stand by.”

Politico New York recently tallied at least 151 appearances Rajkumar has made with the mayor, most of them at events far from her Queens district.

Rajkumar, meanwhile, has tried to depict Williams as missing in action.

"We need a public advocate, not a public absentee,” she said Thursday.

Rajkumar mocked Williams in a series of cartoon caricatures on social media, including one that shows him napping while she maintains a busy schedule.

That appeared to echo recent comments by Adams, who said last month, “The public advocate wakes up at noon. He takes a nap until two.”

Acting as a check on the mayor is part of the job of public advocate, who’s also first in the line of succession to the mayor. But while the role is somewhat ill-defined, Williams points to his record.

“We’re just really proud that we’ve had the ability to be on the ground and lift up issues that people care about, whether it’s affordability, public safety,” he said. “And also just being an accomplished legislator. We’ve passed more pieces of legislation than all previous public advocates combined.”

Leaning on her background as a lawyer, Rajkumar promises to sue local and federal agencies, including the city’s Department of Homeless Services and the MTA, in her first 100 days.

“I’m going to transform the public advocate’s office into a legal powerhouse,” she said.

Another challenger on the primary ballot is businessman Marty Dolan, a centrist Democrat who ran for Congress last year against Rep. Alexandria Ocasio-Cortez.

But Rajkumar leads the field in fundraising, with $1.4 million on hand as of the most recent campaign finance filing, compared to $1.1 million for Williams.

That’s allowing her to place ads on TV and on LinkNYC kiosks around the city. Rajkumar is also backed by the outside group United New Yorkers for Progress, which says it’s raised close to $400,000 to boost her candidacy.