A top ballot-access consultant for Robert F. Kennedy Jr.’s independent presidential campaign was arrested on assault charges at a luxury Manhattan hotel early last Saturday morning, the New York Police Department said.

The consultant, Trent Pool, 37, was taken into custody at the Soho Grand Hotel and charged with criminal obstruction of breathing and assault, the police said. An unidentified 25-year-old woman said he had “wrapped his hand around her neck making it hard for her to breath and then struck her in the face with a closed fist,” according to a police representative. The woman declined medical attention at the scene.

The arrest was reported earlier by Mediaite.

Stefanie Spear, a spokeswoman for the Kennedy campaign, said Friday: “Trent is a contractor. He tells us that the alleged incident never occurred.”

Gregory Esposito, a lawyer for Mr. Pool, said, “Mr. Trent Pool is innocent of all charges, and we look forward to demonstrating so in court.”

Mr. Pool, a Texas-based petition circulator, has played a central role in Mr. Kennedy’s ballot-access efforts, according to court records and three people familiar with the campaign who spoke on the condition of anonymity to discuss its internal workings. As an independent candidate, Mr. Kennedy faces an uphill battle to get on the ballot in all 50 states, an endeavor that could cost tens of millions of dollars.

The Kennedy campaign has paid one of Mr. Pool’s firms, Accelevate 2020, nearly $390,000 for ballot consulting. (Accelevate has also done work this election cycle for the presidential campaigns of Marianne Williamson, a Democrat, and Nikki Haley, a Republican, records show.)

Mr. Pool has been instrumental in promoting an aggressive legal strategy to challenge state signature-gathering rules, the people familiar with the campaign said. Accelevate and Mr. Pool joined in a federal lawsuit in Utah filed by the Kennedy campaign this year, seeking to extend the state’s ballot deadline and loosen its rules on who can gather signatures. Paul A. Rossi, a lawyer who has represented Mr. Pool in similar lawsuits over the years, is the Kennedy campaign’s main ballot access lawyer.

A super PAC backing Mr. Kennedy, American Values 2024, has also worked with Mr. Pool, according to public records and two of the people familiar with Mr. Kennedy’s campaign.

From December to the end of March — the latest date for which campaign expense reports are available — American Values paid $2.4 million to companies for ballot access work, including $1.2 million to a newly formed firm called Public Appeal LLC, which was set up last year and whose leadership includes Mr. Pool and his brother, public records show.

Tony Lyons, one of the super PAC’s leaders, did not immediately respond to a request for comment.