Nina Jankowicz’s new book, “How to Be a Woman Online,” chronicles the vitriol she and other women have faced from trolls and other malign actors. She’s now at the center of a new firestorm of criticism, this time over her appointment to lead an advisory board at the Department of Homeland Security on the threat of disinformation.

The creation of a board, announced last week, has turned into a partisan fight over disinformation itself — and what role, if any, the government should have in policing false, at times toxic, and even violent content online.

Within hours of the announcement, Republican lawmakers began railing against the board as Orwellian, accusing the Biden administration of creating a “Ministry of Truth” to police people’s thoughts. Two professors writing an opinion column in The Wall Street Journal noted that the abbreviation for the new Disinformation Governance Board was only “one letter off from K.G.B.,” the Soviet Union’s security service. Alejandro N. Mayorkas, the secretary of the Department of Homeland Security, has found himself on the defensive. In a television interview on CNN on Sunday, he insisted that the new board was a small group, that it had no operational authority or capability and that it would not spy on Americans.

“We in the Department of Homeland Security don’t monitor American citizens,” he said.

Mr. Mayorkas’s reassurance did little to quell the furor, underscoring how partisan the debate over disinformation has become. Facing a round of questions about the board on Monday, the White House press secretary, Jen Psaki, said that it represented a continuation of work that the department’s Cybersecurity and Infrastructure Security Agency had begun in 2020, under the previous administration.

Its focus is to coordinate the department’s response to the potential impacts of disinformation threats — including foreign election influence, like Russia’s in 2016 and again in 2020; efforts by smugglers to encourage migrants to cross the border; and online posts that could incite extremist attacks. Ms. Psaki did not elaborate on how the department would define what constitutes extremist content online. She said the board would consider making public its findings on disinformation, although “a lot of this work is really about work that people may not see every day that’s ongoing by the Department of Homeland Security,” she said.

Many of those criticizing the board scoured Ms. Jankowicz’s past statements, online and off, accusing her of being hostile to conservative viewpoints. They suggested — without basis — that she would stifle legally protected speech using a partisan calculus.

Two ranking Republican members of the House committees on intelligence and homeland security — Michael R. Turner of Ohio and John Katko of New York — cited recent comments she made about the laptops of Hunter Biden, the president’s son, and about Elon Musk’s bid to purchase Twitter as evidence of bias.

Ms. Jankowicz, 33, has suggested in her book and in public statements that condescending and misogynistic content online can prelude violence and other unlawful acts offline — the kinds of threat the board was created to monitor. Her book cites research into virulent reactions that prominent women have faced, including Vice President Kamala Harris after her nomination in 2020.

Ms. Jankowicz has called for social media companies and law enforcement agencies to take stiffer action against online abuse. Such views have prompted warnings that the government should not police content online; it has also motivated Mr. Musk, who has said he wants to purchase Twitter to free its users from onerous restrictions that in his view violate freedom of speech.

“I shudder to think about, if free speech absolutists were taking over more platforms, what that would be like for the marginalized communities around the world, which are already shouldering so much of this abuse, disproportionate amounts of this abuse” Ms. Jankowicz told NPR in an interview last week about her new book, referring to those who experience attacks online, especially women and people of color.

A tweet she sent, using a portion of that quote, was cited by Mr. Turner and Mr. Katko in their letter to Mr. Mayorkas. The note requested “all documents and communications” about the creation of the board and Ms. Jankowicz’s appointment as its executive director.

The board quietly began work two months ago, staffed part time by officials from other parts of the large department.

According to a new statement released on Monday, the department said the board would monitor “disinformation spread by foreign states such as Russia, China, and Iran, or other adversaries such as transnational criminal organizations and human smuggling organizations.” The statement also cited disinformation that can spread during natural disasters, citing false information about the safety of drinking water during Hurricane Sandy in 2012.

It’s not the first time the Department of Homeland Security has moved to identify disinformation as a threat facing the homeland. The department has joined the F.B.I. in releasing terrorism bulletins warning that falsehoods about the 2020 election and the Capitol riots on Jan. 6, 2021, could embolden domestic extremists.

Mr. Mayorkas has defended Ms. Jankowicz, calling her “a renowned expert” who was “eminently qualified” to advise the department on security threats that germinate in the fecund atmosphere online. At the same time, he acknowledged mishandling the announcement of the board — made in a simple press statement last week. “I think we probably could have done a better job of communicating what it does and does not do,” he told CNN.

Ms. Jankowicz has been a familiar commentator on disinformation for years. She has worked for the National Democratic Institute, an arm of the National Endowment for Democracy that promotes democratic governance abroad, and served as a fellow at the Woodrow Wilson International Center for Scholars in Washington.

As a Fulbright fellow, she worked as an adviser to the Ukrainian government in 2017. Her 2020 book, “How to Lose the Information War: Russia, Fake News and the Future of Conflict,” focused on Russia’s weaponization of information. It warned that governments were ill-prepared and ill-equipped to counteract disinformation.

A quote posted on her biography on the Wilson Center’s website underscores the challenges for those who would fight disinformation.

“Disinformation is not a partisan problem; it’s a democratic one, and it will take cooperation — cross-party, cross-sector, cross-government, and cross-border — to defeat,” it says.