A federal judge in Manhattan sentenced a Florida woman on Tuesday to a month in prison for her role in a brazen scheme to steal the diary of President Biden’s daughter and sell it to a right-wing group in the hope of disrupting the 2020 election.

The conduct of the woman, Aimee Harris, “was despicable and consequently very serious,” Judge Laura Taylor Swain of Federal District Court for the Southern District of New York said before handing down a punishment.

Ms. Harris, 41, tested the patience of prosecutors and the judge overseeing the case after she missed repeated sentencing dates, jeopardizing what otherwise appeared to be a likely path to probation. In August 2022, she pleaded guilty to conspiring to transport the stolen diary to New York, where she met with employees of the group, Project Veritas, and sold it for $40,000 just weeks before the election.

The judge also sentenced her to three years’ probation, along with three months of home confinement, and ordered her to pay back the money she earned from the sale.

The sentencing of Ms. Harris reflects the seriousness of the government’s efforts to deter people from interfering in elections. That includes former President Donald J. Trump, who is awaiting federal trial in Washington on charges of trying to subvert the outcome of the 2020 race.

In a statement provided to the court, Ms. Biden described what happened to her as “one of the most heinous forms of bullying.”

Initially federal prosecutors had recommended Ms. Harris face up to six months of home confinement and three years of supervised released, while her lawyers had requested probation. But her sentencing was pushed back repeatedly — a dozen times — in part because Ms. Harris claimed she had child care issues or was sick.

At a scheduled hearing in late January, Ms. Harris called the court from an emergency room hospital, prompting Judge Swain to describe the situation as “highly irregular.” At a hearing in February, the judge told Ms. Harris that the reasons she had cited in seeking a delay were “matters of great concern for the court.”

Prosecutors, exasperated, asked the judge this month to impose a sentence of four to 10 months in prison, saying Ms. Harris had “repeatedly and consistently engaged in tactics to improperly delay this proceeding.” They accused her of misrepresenting the nature of her child care, failing to get an identification card so she could travel to New York and flouting the court’s rules.

Judge Swain finally threatened to have her arrested and brought to New York by U.S. marshals if she did not comply with the court’s orders.

After her guilty plea in August 2022, prosecutors said that Ms. Harris was later arrested and charged with driving under the influence with property damage and had tested positive for marijuana. The judge ordered her to undergo treatment for alcohol abuse.

Mr. Harris claimed that the diary had been abandoned, discarded at a friend’s house where she had been staying. But prosecutors said that in August 2020, she stole the diary, which President Biden’s daughter Ashley Biden had left at the house to store along with other personal items.

Ms. Harris then enlisted the help of a friend, Robert Kurlander, to sell the diary. Eventually, the pair found a buyer in Project Veritas, with each making $20,000. The two later returned to the house, taking other items belonging to the president’s daughter to confirm she was in fact the diary’s author.

Mr. Kurlander, 60, who also pleaded guilty and has cooperated with the Justice Department’s investigation into the theft, is scheduled to be sentenced later this year. On Friday, prosecutors asked for a six-month delay. Mr. Kurlander was previously convicted of fraud in a federal court in Florida. He also faces prison time but unlike Ms. Harris decided to cooperate with prosecutors.

As part of its investigation, the F.B.I. searched the homes of three former employees of Project Veritas, including its founder, James O’Keefe, but so far none of them have been charged. All three have since left the group.

Mr. O’Keefe was pushed out of Project Veritas after employees denounced his management style along with questionable spending. Hannah Giles, who succeeded him as chief executive, laid off employees.

But she abruptly quit in December. She wrote on social media that she had “stepped into an unsalvageable mess — one wrought with strong evidence of past illegality and past financial improprieties.”

In December, a federal judge ruled that prosecutors could review hundreds of documents related to the theft of the diary. Project Veritas had claimed that the materials were protected under the First Amendment and that “disclosure to the government would violate their constitutional rights, constituting irreparable harm.”

Lawyers for Mr. O’Keefe and the two other former operatives of Project Veritas — Spencer Meads and Eric Cochran — asked the judge to temporarily halt that order as an appeal moved forward. But the judge denied the motion in January, noting that additional delay could “frustrate the investigation and raise concerns about witness recollection, evidence availability and statutes of limitations.”

Mr. Meads has appealed the ruling. The status of the investigation remains unclear but Mr. Kurlander’s delayed sentencing until October most likely means prosecutors have not ended their pursuit of Mr. O’Keefe.

Over the course of the inquiry, investigators obtained evidence that indicated that Ms. Harris hoped not only to profit from selling the diary to the group but also to hurt Mr. Biden’s chances of defeating Mr. Trump.

“Stealing personal belongings of a candidate’s family member, and selling them to an organization to exploit them for political gain, was wrong and illegal no matter the political agenda,” prosecutors said in a sentencing memo. “Such criminal conduct does not merely harm the victim, but seeks to undermine the political process.”

The memo added, “The calculus must be clear that criminal conduct of this sort will not be tolerated regardless of one’s political affiliation, ideology or motivation.”

Text messages obtained by prosecutors showed that Ms. Harris and Mr. Kurlander knew that they were stealing Ms. Biden’s diary and her other belongings and that the group planned to publicize the contents of the diary, which she had kept while she was recovering from drug addiction.

Olivia Bensimon and Anusha Bayya contributed reporting.