Obama's in-tray

But with the economy in crisis, his stock could easily be consumed by disappointment if his presidency reaches mid-term without showing enough fruits.

Totemic changes in US attitudes on the environment, human rights and foreign relations can be expected in his first 100 days.

But complex healthcare reforms beat Bill Clinton's administration and could easily run into the sand again. And a looming row over union rights has to be faced when this week's champagne bottles have been cleared away.

ECONOMY

A trillion-dollar stimulus aims to support four million jobs, with an emphasis on priority areas such as green energy, healthcare and education. Tax breaks and, less popularly, a further bailout for the banks are part of the plan. "The way I see it, the first job is to get people back to work," he has said.

IRAQ

A US withdrawal by 2010 is expected, at a rate of up to two combat brigades a month. Officials say he will keep his pledge given in July "to end this war responsibly and deliberately but decisively".

AFGHANISTAN

The 44th President will redeploy troops to the war against the Taliban. Officials expect more than 20,000 extra troops to be sent by this summer, doubling the US force there. Mr Obama has made clear he wants allies including Britain to send more, which could cause friction.

GUANTANAMO BAY

By the weekend he is expected to approve plans to close the US detention centre at Cuba, which has been tainted by allegations of torture and abuse. However, it cannot actually close until around 250 detainees are dispersed. Some may come to Britain. Waterboarding and other harsh interrogation techniques are expected to be outlawed by executive order.

CLIMATE CHANGE

A sea-change in policy from the Bush era, with targets for an 80 per cent cut in greenhouse gases by 2050 and a carbon emissions permit scheme for industry.

FOREIGN POLICY

His first big foreign speech will be in a Muslim nation, say allies - perhaps Indonesia, where he lived briefly as a child. Officials also say he will woo "old Europe" powers. He will need goodwill to make progress on the Middle East, which he calls a "day one priority". He may press Israel for concessions.

HEALTHCARE

Big promises to cut insurance costs and give affordable protection to the poor will mean tough battles with insurance and pharmaceutical firms. Mr Obama has appointed former Senate majority leader Tom Daschle as health czar to tackle an area that has bedevilled previous reformers.

TRADE UNION RIGHTS

Plans to make firms recognise unions after employee votes - not always secret ballots - threaten to consume political capital but the 44th President is under pressure to honour a commitment.

BRITAIN

Obama intends to build relations with "old Europe" while turning towards Asia. His economic stimulus is just what Gordon Brown hoped for, though there is concern that America will go soft on free trade.