One question looming over Hillary Rodham Clinton’s forthcoming book: Will she outline policy disagreements with President Obama or other members of his administration? (JASON REED/REUTERS)

Hillary Rodham Clinton is rushing to finish a memoir of her time as secretary of state, something friends see as an urgent mission to frame a key part of her legacy as she readies for a possible presidential campaign.

But her Republican critics are racing to define Clinton’s record first — preparing a massive opposition-research effort designed to challenge her recounting of events and undermine the book’s credibility.

The war over Clinton’s tenure as the nation’s top diplomat will play out in coming months as a proxy skirmish for a potential 2016 campaign. For Clinton, the political imperative is clear: to lay claim to key accomplishments in foreign policy and short-circuit persistent attacks on her judgment from the right.

Republicans are stepping up criticism of her handling of the deadly 2012 attacks in Benghazi, Libya, on the heels of last week’s bipartisan Senate report that, while not blaming Clinton directly, said the assault was preventable. In addition, her successor, John F. Kerry, is winning plaudits for diplomatic breakthroughs on Iran and other issues that Clinton did not achieve.

Clinton sees her book — to be published by the summer — as a chance to showcase her leadership role in events including the Arab spring, the overthrow of Moammar Gaddafi in Libya and the killing of Osama bin Laden, according to people familiar with the plans. A key question looming over the project is whether Clinton will detail areas of policy disagreement with President Obama or other members of his administration.

The timing would allow her to mount a splashy book tour followed by a series of campaign events on behalf of Democratic candidates ahead of the midterm elections in November.

‘Conventional wisdom’

Concern is rising among Democrats in Clinton’s orbit that she is at risk of losing control of one of the most pivotal parts of her biography. One friend worried that Republicans are already succeeding in muddying her record at State.

“It’s almost becoming a kind of conventional wisdom that there were minimal accomplishments,” said the friend, who, like some others, spoke on the condition of anonymity to talk candidly without alienating the Clinton camp. “The concern about this talking point catching hold has lent more urgency to getting the book done.”

She will have help: Correct the Record, a group started by Clinton ally David Brock to defend her in anticipation of a 2016 campaign, has hired researchers to study her State Department tenure. Officials said the project has Clinton’s blessing, and her team is assisting with the research.

Correct the Record is developing digital and social-media campaigns that would complement Clinton’s book, including building an interactive map that would let users click on any country to find out specific things Clinton did there as secretary, spokeswoman Adrienne Elrod said.

“Secretary Clinton’s story is a very American story — a success story,” Elrod said.

On the other side, America Rising, started by former Mitt Romney campaign manager Matt Rhoades and GOP operative Tim Miller, has set up a war room to prepare for the book’s release. Researchers are scouring every public comment Clinton has made, as well as briefing transcripts, inspector general reports and other records — all in preparation to blow the whistle on any alleged exaggerations or mistruths.

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“The challenge for her with this book is to highlight a tangible accomplishment that voters can identify,” Miller said.

Friends said Clinton is approaching the book project methodically and with characteristic caution — one called it “an over-careful environment.” She is aware, they said, that every word will be parsed in the run-up to 2016, especially if she draws policy distinctions with Obama.

“The carefulness with which they’re approaching it is significant,” said another Clinton friend. “She’s writing for the moment, in the expectation that she’s going to run for president, so she has to be very careful with what she says.”

Clinton has devoted much of December and January to writing, working closely with a small staff of researchers and writers and regularly consulting her circle of longtime advisers. She has debriefed former State Department colleagues at her home in Washington and reviewed notes and classified documents as she composes reflections.

“She’s very animated about it,” said former congresswoman Ellen Tauscher, a Clinton friend who served with her as an undersecretary of state. “This is the first time in a very long time that she gets to talk about important, weighty things as she thinks of them, unencumbered by the responsibilities of office or serving in the administration. . . . It’s almost like this is Hillary unencumbered.”

Clinton’s aides said she is not finished with the manuscript, and some people close to her said the project is taking longer than she had hoped. “It’s a bit of a struggle to get it done,” said the friend who was worried about GOP efforts. “She is not necessarily a natural writer.”

Clinton’s spokesman, Nick Merrill, and her adviser Philippe Reines declined to answer questions about the book or about Clinton’s writing process.

“If you can’t judge a book by its cover, as the saying goes, you certainly can’t thoughtfully do so with a book that doesn’t even have a cover because the pages in between aren’t written,” Merrill said. “So it’s very difficult to make observations before then.”

Former Pennsylvania governor Edward G. Rendell, a Clinton confidant who is encouraging her to run in 2016, said he expects the book to show that she was “a groundbreaking secretary of state.”

But, Rendell added: “All autobiographies have limited impact because people expect autobiographies to tell one side of the story. The people who will buy and read her memoir are people who are already strong Hillary supporters. I found when I did my book that 95 percent of purchases were from people who were big Ed Rendell enthusiasts.”

‘Dramatic moments’

In coming weeks, Clinton’s publisher, Simon & Schuster, is expected to announce a publication date and release an image of the cover. A title has not been announced. (The release date is listed on Amazon’s Web site as June 1, but officials said that is not accurate.)

Clinton’s agent, Bob Barnett, declined to talk about the book, and her advance has not been released. In 2000, Barnett sold the rights to Clinton’s first memoir, “Living History,” to Simon & Schuster for $8 million.

Simon & Schuster announced that Clinton’s new book will use “dramatic moments” from her four years as secretary to frame her thoughts on U.S. foreign policy, as well as to address global trends in economics, climate change, human rights and other areas. The book is not expected to recount her experiences in the 2008 presidential campaign.

Helping Clinton write the book are speechwriter Dan Schwerin and researcher Ethan Gelber, both former State Department aides, as well as Ted Widmer, a former White House speechwriter to Bill Clinton.

Hillary Clinton also has been discussing the book with close advisers. Two family friends said the sessions have included Huma Abedin, Cheryl Mills, Maggie Williams, Evelyn Lieberman and Melanne Verveer. Merrill disputed that but would not elaborate.

At the State Department, where portraits of Clinton have long since disappeared from the walls, Kerry loyalists regard her forthcoming memoir with trepidation. Privately, they say they see the book as a potentially unwelcome distraction from Kerry’s active work in the job.

Jay Jacobs, a former New York Democratic Party chairman and Clinton friend, said: “Every secretary of state builds on the experience of their predecessors. A lot of what you’re seeing now that’s playing out in terms of Iran and other areas is all part of the hard work that Hillary Clinton did in the preceding term. When she talks about it in her book, we’ll get a better sense of the broader issues she dealt with and the progress she made.”

Anne Gearan contributed to this report.