Washington ? It may be moot and it certainly is presumptuous, but I would be less than honest with readers if I did not say what I believe: Making Hillary Rodham Clinton the secretary of state in Barack Obama’s administration would be a mistake.

I do not doubt she could do the job — and do it well. I have been a fan of the former first lady’s since I covered her efforts for health care reform 15 years ago. What I saw in the recent campaign for the Democratic presidential nomination was convincing evidence of her physical stamina and moral courage and of her capacity to improve her own performance at every step of the process. I admired her readiness to endorse and campaign hard for Obama after her own candidacy fell short.

Equally, I admire Obama’s readiness to reach out to former rivals and enlist their help in the governing enterprise he is launching. His serious discussions with Clinton, John McCain and Bill Richardson, among others, are testaments to his sincerity in wanting to move beyond the partisanship and personal differences that too often poison the atmosphere in Washington.

What, then, is the problem? Clinton is the wrong person for that job in this administration. It’s not the best use of her talents and it’s certainly not the best fit for this new president.

What Obama wants and needs in the person running the State Department is a diplomat who will carry out his foreign policy. He does not need someone who will tell him how to approach the world or be his mentor in international relations. One of the principal reasons he was elected was that, relying on his own instincts, he came to the correct conclusion that war with Iraq was not in America’s interest. He was more right about that than most of us in Washington, including Hillary Clinton.

Of course, he will benefit from the counsel and the contacts that his secretary of state can offer. But remember, he provided another and probably more expert source of that wisdom when he picked Joe Biden, the veteran chairman of the Senate Foreign Relations Committee, as his vice president. The last thing Obama needs is a secretary of state carving out an independently based foreign policy. He needs an agent, not an author.

Even if Hillary Clinton were ready to play such a subordinate role, which she might be, in return for a promise that her voice would be heard in the most serious policy debates, the presence of Bill Clinton makes that a doubly difficult assignment. The former president has, through the Clinton Global Initiative and his own extensive foreign travels and worldwide contacts, made himself a force in international affairs. It would be unfair, and unlikely, for him to shut down his own private foreign policy actions because they might conflict with his wife’s responsibilities. But foreign leaders would inevitably see Bill Clinton as an alternative route toward influencing American policy. And he is unlikely to remain silent.

Some commentators have suggested that Hillary Clinton is frustrated by her lack of seniority in the Senate and the fact that she is not yet a chairman of any of the committees handling big policy areas. I find that a curious notion.

Her influence, which is vast, does not rest on seniority. It rests on the respect she has won from colleagues in both parties for her hard work, her preparation and her mastery of the substance of policy. Senators want her support for their efforts, and they are — both Republicans and Democrats — eager to join hers, because they know she commands a unique audience both in the Capitol and across the country. That was true in the past and it is even more true after the impressive campaign she ran for the presidential nomination.

If Clinton can be of service to Obama in Foggy Bottom, she can be of even greater value as an ally on Capitol Hill.

I hope that is where she will be when January rolls around.

— David Broder is a columnist for Washington Post Writers Group.