She'll bring global star power, a long-standing commitment to improving the status of women and children around the world and muscular promises of military action when U.S. interests are crossed.
The question for Hillary Rodham Clinton, slated to be named secretary of State on Monday by President-elect Barack Obama, is whether she can forge the sort of close relationship with a former rival that is crucial to giving the nation's top diplomat the credibility to get things done.
"What matters most are two things," says James Lindsay, director of the Robert S. Strauss Center for International Security and Law at the University of Texas-Austin. "One, the secretary of State has to have the president's ear. Two, the president has to have the secretary of State's back."
Obama is choosing for his most prestigious Cabinet post an independent-minded policymaker whose world view has been shaped by eight years as a globe-trotting first lady and eight years as a senator with time on the Armed Services Committee. She combines a focus on "soft" issues such as maternal health with rhetoric more hawkish than Obama's on containing Iran's nuclear program and protecting Israel.
She will be taking the lead on a crushing set of global challenges, including repercussions from last week's terrorist attacks in Mumbai, India, which threaten a conflagration on the nuclear-armed subcontinent.
In collaboration with other administration officials, the incoming secretary of State will deal with the withdrawal of U.S. troops from Iraq, efforts to turn around the war in Afghanistan, nuclear programs in such rogue nations as North Korea and Iran, the challenge from a resurgent Russia and growing concerns about global climate change.
Obama's pick is non-traditional on several fronts. Not since James Garfield appointed James Blaine to head the State Department in 1881 has a president chosen a major political rival for the job. What's more, Clinton's grounding in women's rights contrasts with her predecessors, most of whom had pursued careers in academia, the military or law steeped in U.S. relations with major world powers.
The Obama transition office said Sunday that he would unveil his national security team today. Two Democratic sources with firsthand knowledge of the decision confirmed Clinton would be among those named. They spoke on condition of anonymity because they weren't authorized to speak on the record.
Clinton is "a tough pragmatist who understands it's a dangerous world out there, who understands it can be necessary at times to use force and at other times to be able to back your diplomacy with the threat of force," says Martin Indyk, a former assistant secretary of State and ambassador to Israel who is close to Clinton.
"On the other hand, she has shown a very deep commitment to the causes of human rights, women's rights in particular, and the pursuit of peace and resolution of conflict."
When Clinton decided to run for the Senate in 2000, she launched her campaign with a "listening tour" to hear from New York voters. When she began her presidential campaign in 2007, she announced a similar "listening tour" through states with early primaries and caucuses.