By Paul Reynolds
World affairs correspondent BBC News website
It was never going to be easy to be secretary of state in the shadow of a president who won the Nobel Peace Prize within months of taking office.
And that is what Hillary Clinton has perhaps found. President Obama has made such an impact on the world, partly from not being George W Bush, that she is sometimes left as an also-ran. Just as she was in the presidential elections.
It is the president who has re-fashioned American foreign policy from one widely seen as confrontational, into one in which he says he seeks engagement.
How much of an adviser can she really be to someone who knows his own mind?
He, not Hillary Clinton, has set the agenda for America.
It was he who insisted on taking time with his advisers to debate sending reinforcements to Afghanistan.
It was he who reached out to the Muslim world.
It was he who insisted to the Israelis that they had to freeze settlements if there were to be further Middle East peace talks.
It was he who held out his hand to Iran, hoping for an unclenched fist. It will be he who will determine whether at some stage to move from sanctions to military action.
It was he who led the US negotiations over global warming, an issue which has not enthused her much.
Hillary Rodham Clinton (as she prefers to be called, emphasising her own family name as well as that of her husband) is finding it a hard task to fashion a distinctive diplomatic role for herself.
That is not uncommon among secretaries of state. Many have been swallowed up by history. Only those with strong personalities and willing and able to grasp the reins of foreign policy (under a president willing to leave that to them) have thrived at the time and in the memory.
Hillary Clinton is now happy for Barack Obama to answer the 3am call
Henry Kissinger under President Nixon and John Foster Dulles under President Eisenhower were modern titans. George Schultz for Ronald Reagan and James Baker for George Bush senior did some hard deal-making in their day. But who studies the works of Christian Archibald Herter, also a secretary of state under Eisenhower, and William P Rogers, who preceded Kissinger under Nixon?
It was a risk for Barack Obama to bring his rival into the administration's tent. She is at heart more hawkish than he is and has had to tone this down. A crisis could yet arise when her instincts clash with his.
She has also had to accept that the infamous "0300 call" election advertisement was an empty, and unedifying, threat, which diminished her.
The ad was hardball stuff and attacked her election rival's lack of foreign policy experience. Over pictures of sleeping children, the commentary said: "It's 3am and your children are safe and asleep. But there's a phone ringing in the White House... who do you want to answer the phone?"
Hillary Rodham Clinton is now happy for Barack Obama to answer that phone.
She also has strengths. She is well-known and well-liked by her international colleagues and audiences. As Joe Klein of Time magazine put it: "She is an international celebrity with a much higher profile than any of her recent predecessors and the ability - second only to the President's - to change negative attitudes about the US abroad."
The administration is only a year old. Secretary Clinton will not be dissatisfied with her image. It is her achievements that remain in doubt.
How much of an adviser can she really be to someone who knows his own mind? Is she skilled enough at the hard graft of negotiating to be able to deliver what the president wants? And what happens if they have a major disagreement?