About eight months ago I was visiting an old friend in San Francisco and, for reasons I couldn't then explain, I found myself betting him and his son $100 each that the Democrats would lose their majority in both houses of Congress in the United States mid-term elections this November.

It seemed like easy money to them then - surely the Democrats wouldn't lose the Senate - but I think they are going to owe me $200.

Much is being made of this in the media at the moment - how disappointed Obama's former supporters are, how angry and mobilised the Republican "base" are, how extremely hostile to him the new Republican-controlled House and Senate will be. How can he be so calm about this? Why doesn't he get out there and fight?

Well, he has made a few fairly fiery speeches recently, but he knows speeches won't do much good. His supporters are disappointed because it has been a long, grim recession and, for most Americans, it is not over.

Obama couldn't get another economic stimulus bill through Congress at this point even if he thought it was a good idea, so he can't hurry the recovery up.

Some of those who voted Democrat in 2008 are also cross because Obama has not brought American troops home from Afghanistan as quickly as they hoped, or hasn't got any legislation about climate change through Congress, but he can't deliver on those things this year either.

All he has at his disposal are words, and they won't be enough to re-motivate disillusioned Democrats.

The Democrats lack all conviction while the Republican base is filled with passionate intensity. Obama's approval rating of 44 per cent is not especially low for a US President two years into his first term - Ronald Reagan and Bill Clinton were considerably lower at this point in their presidencies - but most of his supporters won't bother to vote in this election, while almost all of his enemies will.

If you really believe that your country has been hijacked by a Muslim communist who was born in Kenya (or a cannibal troll who was born in Mordor, or whatever), then you will certainly get out and vote. If all of the retired white people vote, and only the usual mid-term proportion of all the other demographics does, then the Democrats will lose both houses of Congress. So why isn't Obama more worried about it?

He will certainly regret that so many long-serving Democratic senators and congressmen are going to lose their seats this northern autumn, but who controls the Congress for the next two years really does not matter much to him.

He can't hope to get any more legislation passed by even the current Congress since the Democrats lost their "super-majority" of 60 seats in the Senate last January, so what's the difference?

Nor does Obama have to get more legislation through Congress right now. It would be nice to have a tough climate change bill, but from a political point of view there is no new law that he simply must pass before he faces re-election himself in 2012.

Indeed, he stands a good chance of winning a second term in 2012, in large part because of what is going to happen next month.

Getting majorities in both houses of Congress will leave the Republicans nowhere to hide on the critical issue of cutting the huge federal deficit.

They have already said that they will not raise taxes - even for those earning more than US$250,000 ($336,000) a year - and they have pledged not to cut defence spending. What's left? The only other big-ticket items in the budget are entitlements: healthcare and pensions.

The US has not yet gone through the painful debate about how to tame the deficit that has already happened in most European countries, but it will have to do so soon. That poses a particular problem for Republicans, because if they will not raise taxes on the rich or cut defence spending, then they have to support brutal cuts in healthcare and pensions or lose all credibility as deficit-cutters. But cutting entitlements would alienate the Republicans' most important demographic: older white people.

They will not risk that. By contrast, the Democrats would not be alienating their own base if they cut defence spending and raised taxes on the rich, so they can be coherent and consistent on the topic.

A Republican-controlled Congress may well come to be seen as an obstacle to fiscal responsibility, even by many Republicans.

Make the further, quite reasonable assumptions that the US economy will be growing strongly again by 2012 and that US troops will be gone from Iraq and on their way out of Afghanistan, and you have a credible scenario in which the Democrats win back both houses of Congress as well as re-electing Barack Obama.

Meanwhile, Obama can veto any Republican attempt to repeal the legislation he has already got through Congress, and he will retain a free hand in foreign affairs.

He could even try to get new legislation on immigration through Congress. It wouldn't pass, but he could thereby lock up the Latino vote. No wonder he looks calm.

* The updated and expanded second edition of Gwynne Dyer's best-selling book, Climate Wars, has just been published in New Zealand by Scribe.