Barack Obama left Chicago for a last pre-presidential Christmas in Hawaii at the weekend. Before he went, with characteristic discipline and orderliness, he completed the announcements of nominations to fill the top jobs in his administration, ensuring that those happy strolls with his family into Pacific sunsets will not be spoilt by any last-minute decision-making.

It has been a remarkably quick process. Less than seven weeks after the election, and with four weeks still to Inauguration Day, the President-elect now has in place all his Cabinet nominees, as well as his key White House advisers in the national security and economic policy fields.

Inevitably, the selections, many of them surprising, have encouraged energetic speculation about what course the Obama presidency will take through the terrifying maze of economic and political challenges that confront the United States.

We should be careful not to read too much into them. In a presidential system, of course, it is the chief executive who determines the direction of administration policy. Unlike in the constitutional arrangements of a parliamentary model, the various Cabinet members have very little independent power base of their own. What's more, thanks to the separation of powers in the US Constitution, their limited authority is constrained even further by a co-equal Congress.

And yet the identity of the team still matters, in part because, for all the legal limitations, its members still have important executive and advisory roles, but also because the choices tell us something about the president's own inclinations.

If there's one identifying theme running through Mr Obama's multiple choices so far, it is moderation. Any fears (or, in some places, hopes) that the new president would install some radical team committed to turning America sharply towards the Left have been contradicted by the facts.

The essentially conventional nature of his national security team - Hillary Clinton at State, Robert Gates staying on at Defence and US Marine General James Jones as National Security Adviser - suggest no big break there.

In the economic sphere, where the new president faces his sharpest challenge, he has also gone for a mostly centrist outfit. The two key members are Tim Geithner as Treasury Secretary and Larry Summers as his chief White House adviser.

Mr Geithner, a cerebral young technocrat who eschews publicity, cut his policymaking teeth in the Treasury during Bill Clinton's Administration, where his mentors were Mr Summers and Robert Rubin. He is inevitably associated with that quintessentially “new” Democratic approach to economic management under Mr Rubin, with its emphasis on balanced budgets and pro-market policies at home and internationally. It is worth remembering that the fiercest critics of “Rubinomics” in those days were lefty politicians and commentators, such as Joseph Stiglitz, the Nobel prize-winning economist, who spent a good deal of time attacking Mr Geithner and his bosses for their insufficient concern for the disadvantaged.

Even more striking, Mr Geithner has spent the past year as one of the three key players in Washington's response to the financial crisis. As president of the New York Federal Reserve, he can claim co-authorship with Henry Paulson, George W Bush's Treasury Secretary, and Ben Bernanke, the Fed Chairman, for almost all the decisions made - from Bear Stearns to Lehman Brothers to Fannie Mae and Freddie Mac to the Troubled Asset Relief Programme.

You can argue about the merits of these decisions, but you would be hard-pushed to say that Mr Geithner has diverged in any way from the Wall Street-Washington consensus on the response to the biggest economic challenge of our times.

Mr Summers is more intriguing. Brilliant and bombastic, he, too, established a reputation in the 1990s as a particularly clever advocate of a sort of post-Keynesian economic consen- sus that emphasised the virtues of markets and government restraint. And yet Mr Summers, who will have the president's ear on a daily basis, is harder to pin down. His political instincts, when he lets rip, suggest a more traditional left-wing cast. He has been an articulate advocate, for example, for Mr Obama's plan to raise taxes on the wealthiest Americans in the past year.

There are other members of Mr Obama's economic team but they are unlikely to be anywhere near as influential as these two key figures. Paul Volcker, the former Federal Reserve Chairman, with a roving brief to advise on the financial crisis, is no shrinking violet, but he is unlikely to be a central figure.

From a policy perspective, the direction of policy will depend on the advice Mr Obama gets from Mr Summers and Mr Geithner and how those two work together. For Mr Summers, the next year is crucial - not merely because of the immediacy of the need to deal with the financial crisis, but because in a year's time Mr Bernanke's chairmanship of the Fed will be up for renewal or repla- cement and Mr Summers has made no secret of his desire to move there.

For Mr Geithner, one-time protégé of Mr Summers, the relationship with his former boss is bound to be intriguing. Both were quick to realise that the scale of the global economic crisis was unusually large - Mr Summers was writing in apocalyptic terms about it a year ago, at about the same time that Mr Geithner was pressing inside the Fed for urgent action. A year later they have an historic opportunity to put the world back together again.

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