When Doris Kearns Goodwin first published Team of Rivals, her 2005 biography of Abraham Lincoln, it sold well - but not as well as it is selling now. This is partly because Barack Obama has said that he is reading Lincoln's writings for their wisdom and humility, but mainly because signs that he, like Lincoln, plans to co-opt rivals into his Cabinet have dominated American political debate for the past week.

Historical precedent is not as auspicious as the President-elect may think. Lincoln's top appointees embarrassed him with corruption scandals, squabbled among themselves and complained about what they saw as his incompetence. But times have changed. The American political landscape of 2008 is unrecognisable from that of 2006, never mind 1860. If change is really coming, Mr Obama's appointments need to reflect as well as lead it.

There are two main reasons for him to reach out to those with whom he competed for power: to neutralise political rancour and to ensure that the biggest jobs go to the best people. Mr Obama must do both, not least because his first confirmed appointments smack less of change than of a ritual return to the 1990s.

Rahm Emmanuel, Mr Obama's chief of staff, served as a political strategist for President Clinton from 1993 to 1998. Tom Daschle, chosen to spearhead healthcare reform, was a senior Democratic senator throughout the Clinton years. Eric Holder, reportedly offered the post of Attorney-General, served as Deputy Attorney-General in the second Clinton term. All three are competent and experienced, but there is - already - a real political risk to Mr Obama of limiting his own momentum by reinstating too many veterans of another era, having campaigned so triumphantly on promises of change.

John McCain and Robert Gates are also veterans, but their inclusion in Mr Obama's team would exploit valuable expertise and lend some substance to his pledge to break out of the Democratic corral. Senator McCain deserves a role championing the new climate change treaty that Mr Obama has promised to support. Mr Gates should stay on as Secretary of Defence.

Both men are Republicans, but neither appointment would be as controversial as that of Hillary Clinton as Secretary of State. It would dismay thousands of volunteers and hundreds of staffers who fought specifically to exclude her in Mr Obama's favour as the Democratic presidential nominee. It would drag Bill Clinton's complex foreign entanglements into an unforgiving spotlight and his world view, solicited or not, into US foreign policymaking. Even so, Mrs Clinton would be the right choice.

In this case qualifications trump the taint of dynastic politics. Mrs Clinton's knowledge of the world is as formidable as her stamina. She knows her own mind and is not afraid to speak it. If this presaged constant argument with Mr Obama it would be an argument against her, but it does not: to be effective, secretaries of state must speak for the President, and the last thing Mrs Clinton wants is to be ineffective. Mr Obama has not shown the news-management skill in his courting of Mrs Clinton that he showed on the campaign trail. But he has shown that he wants serious advice for the serious task of redefining America abroad. Lincoln would approve.