We can now, at last, sleep soundly in our beds at night. With Tony Blair safely back from Sir Cliff's "villa" in Barbados, I can report that George W Bush returned to the Oval Office after the Labor Day weekend with his body and mind refreshed. Physically, he was rejuvenated by cycling in the woods and then speed-boating off the Kennebunkport coast with his dad on the family boat Fidelity III; intellectually, he has been brushing up his French existentialism and Shakespeare, adding to the 60 or so books he has already read this year and the three biographies of George Washington alone he devoured last year.

Lest you think I am fleeing into the realms of whimsy and fantasy to block out the realities of Bush returning to office after the summer to continue a presidency that will last until 2009, it is not I doing so. This is all from the lips of Bush himself and the White House. The latter says that Bush has read between 53 and 60 books already in 2006, and in an interview with NBC just a few days ago Bush himself said: "I was in Crawford and I said I was looking for a book to read, and Laura said, 'You oughta try Camus.' I also read three Shakespeares." Hamlet, the White House later added helpfully, was one of the three Shakespeares.

Yet this surrealist nonsense will not let Bush avoid a looming date on his calendar: 7 November. That day, Americans will flock to the polls in record numbers for the midterm elections - and deliver possibly their definitive referendum on Bush and his presidency. For his entire time in office, Bush has enjoyed the luxury of having both a House and Senate that are Republican-controlled; now he faces the possibility of at least one of them returning to the Democrats, as well as a personal humiliation that would strengthen my edict that before long, Americans will see Bush as second only to Warren Harding (1865-1923) as the worst US president in history.

First, though, one of my famed briefs on American politics - or primers, as Americans say. In the elections that come exactly halfway through each presidential term, all 435 House of Representatives seats, 33 of the 100 Senate seats, and 36 governorships come up for re-election - as well as a host of local positions, going down to the post of dog-catcher in some municipalities. In the Senate, there are currently 45 Democrats and 55 Republicans, and in the House 202 Democrat and 232 Republican seats (plus one Independent); this year the Democrats are defending 18 seats and the Republicans 15 in the Senate, and the Democrats hold 14 of the governorships up for re-election compared with the Republicans' 22.

This is why Bush is already frantically engaged in a spree of 20 speeches centred around the fifth anniversary of the 11 September atrocities, which will culminate in a 19 September address to the UN General Assembly. He is resorting to the familiar tactic dreamt up by Karl Rove that has worked so magically for him since 2001: that he and the Republicans are tough guys when it comes to terrorism, while the Democrats are defeatist wimps. Now he is saying they would even cut the military budget for Iraq if they regain control of Congress - thus leaving American soldiers ill-equipped to win and fight the all-important domestic war against terrorism.

Just a pre-election capture of Osama Bin Laden or a foiled terrorist plot could suddenly push up the Republicans' ratings. Bush's personal ratings actually went up when last month's alleged terrorist plot against planes flying from Britain became hot news here as well as in the UK. Senate and House seats, in any case, are gerrymandered in such a way that far fewer change hands than would happen in Britain even in the event of a seismic political shift: the Democrats need just 15 seats to take the House, but the most recent polls say they are ahead in only 14.

They need just six Senate wins, too, but that is even more iffy. The anti-Clinton midterm Republican uprising of 1994 was one of the major earthquakes in US political history, but resulted in just ten gains in the Senate and 54 in the House. Yet that has been enough to give them control of Congress ever since, except for a brief period in 2000 when the Senate was technically 50:50. We can also be certain that whatever the electorate says in November the Supreme Court will stay well to the right for the foreseeable future, quite probably for decades.

The tide moved in the Democrats' favour over the summer, however. The Big Mo, as the president's father would say, is certainly currently with them. The non-partisan Cook Political Report said earlier this year that 42 House seats could possibly change hands, but has now upped that to 55. It is not only the Iraq disaster that is harming the Republicans, either. The Pew Research Centre says that 55 per cent of Americans report that their incomes are not keeping pace with inflation, and 69 per cent say they are suffering more stress in their jobs than they did a decade ago.

Petrol costs 75 cents a (US) gallon more than it did a year ago, and not long ago even hit the $3 mark - still give- away prices compared with those of Europe, but an outrage to Mr and Mrs America. But politics is fickle: just in the past fortnight, petrol prices have started to fall and if this trend continues (as petroleum specialists are now saying it will) that could turn an anticipated curse for the Republicans into an unexpected fillip.

Thus the outlook, while looking very hopeful for the Democrats and alarming for the Republicans, is infuriatingly uncertain. I have one senior Democrat apparatchik friend who told me she doubts whether the Democrats will take control of either the House or Senate. Minutes later, I was talking to a Republican administration veteran who told me he expects the Republicans to lose both.

Neither was playing the lowering-expectations game, either, because I know both of them too well for that. The Republican friend told me: "I have heard talk of impeachment [over Iraq] - not from Democrats, but from Republicans". The Democrat friend, confounding what she had just said to me, told me that her died-in-the-wool Republican brother had returned that morning from a pancake breakfast at his Masonic Lodge in Alabama and had phoned to tell her of his astonishment at hearing the ferocity of anti-Bush feeling over petrol prices and inflation from fellow Freemasons (who, clearly, are hardly traditional Bush-bashers).

In the meantime, Democrats are salivating over the prospect of taking the Senate seat from the likes of the overly ambitious 48-year-old Rick Santorum of Pennsylvania, a state that went for John Kerry by 2.5 per cent in 2004 but which none the less voted in a far-right self-proclaimed "Christian" Republican like Santorum, best known for being anti-gay, in 2000. This month, he was trailing by 18 points. Senator Conrad Burns of Montana, 71, has been deeply tainted by the Abramoff corruption scandal and is a political twit of the first order - a few days ago he said that the US is confronting a "faceless enemy" who "drive cabs in the daytime and kill at night" - and is lagging three points behind. Senator Mike DeWine, representing the crucial state of Ohio and a moderate by Republican standards, is trailing by six points; Lincoln Chafee, another on the left of the party, by two. Senator George Allen, 54, who has just begun a $10m advertising blitz and is a hot contender for the Republican presidential nomination for 2008, is in serious trouble in Virginia and would see his presidential hopes go up in smoke if he fails to hang on there.

The most crucial bellwether state of all is Tennessee, where a battle is being fought for the seat of my friend Dr Bill Frist, hitherto the Senate Republican leader, who is retiring to concentrate on his campaign for the presidency in 2008. If Congressman Harold Ford, who is only 36 but has represented the state in the House for 12 years, should win, that would indicate a rout of the Republicans; he would also become the first black senator to be elected from the South since the Confederacy began. Bush, recognising the importance of this race, flew to Tennessee on 30 August and raised $1.5m at a fundraiser for Ford's Republican opponent.

Ford's campaign claims its private polls indicate he is two points ahead, but the most recent public ones say he is behind anywhere from one to six points. "You have to take ten points away from any black in opinion polls in the South," says my Tennessee spy, who explains that voters are reluctant to tell pollsters they won't vote for a black candidate. In House races, well-known Republican faces such as J D Hayworth of Arizona and Chris Shays of Connecticut - who recently reversed his pro-war stance - could be Republican casualties.

Yet the Democrats face myriad problems. They should eviscerate the Republicans in November, but I predict they won't. The Republicans are better campaigners and have more money. And above all, the Democrats lack leadership. Republicans in 1994 had Newt Gingrich, a meretricious shyster if ever there was one, but a leader with charisma. This year the Democrats have 66-year-old Harry Reid (who?) as their Senate leader, a bespectacled man who is a cunning political strategist with the charm and charisma of a lamp-post.

Their House leader is Nancy Pelosi, also 66, who is more personable but is not renowned for her intellectual or political prowess. Dr Howard Dean, the 57-year-old chairman of the party and briefly Democratic presidential front-runner in' 04, is a stronger potential leader but is kept shackled by much of the party machine because of his depiction by the media as a wild extremist. Republicans are already enjoying pointing out that poor Pelosi, if the Democrats take the House in November, would become Speaker - and thus president should Messrs Bush and Cheney simultaneously fall under a bus.

Above all, though, this weak (or even non-existent?) leadership means that the Democrats continue to remain paralysed like rabbits in the headlights over what to say or do about the war in Iraq and Bush's relentless mantra that, like John Kerry, they would be weak on terrorism - and his (or, rather, Rove's) fiendishly clever merging of the two in public perceptions. Pelosi has vowed that "we will fight them on national security [and] will not be swiftboated on this issue", but that is exactly what is already under way.

Clintonian pragmatism

It has taken obscure Democrats such as Rocky Anderson, the mayor of Salt Lake City - home of the Mormons and hardly the bastion of radicalism - publicly to denounce Bush as "a dishonest, warmongering, human-rights violating president" whose two terms will "rank as the worst presidency our nation has ever had to endure". The likes of Ford, in contrast, are moving steadily to the right now that serious, post- Labor Day campaigning is under way; that is what Clintonian pragmatism dictates is the necessary course for Democrats.

Whatever happens in November, Bush will have to change fundamentally if he is to achieve anything in his last two years in office - such as his dream of "reforming" pensions. Either he could find himself having to wheeler-deal with a Democratic congressional leadership, which is as hard to envisage as it was under Harding; or he may be left to deal with Republicans in Congress who will have been freed to become openly disenchanted with a president many of them now privately despise, and who are already looking forward to 2008 and switching their loyalties to the likes of John McCain and Rudy Giuliani.

But let us not forget that Bush now heads towards the 2006 midterm elections a stronger man, intellectually emboldened by his summertime absorption of Camus and Shakespeare. In its blithe philistinism, the White House not only told us that one of the Shakespeares was Hamlet - where the boy prince is haunted by the ghost of his father - but that the Camus novel was 'Étranger, which just happens to be about how an alienated European colonialist hunts down and kills an Arab and then awaits execution for his crime.

If the Bush White House tried to be a parody of itself, it could do no better than this; you laugh or you cry. The newly "eclectic" Bush - his own word, though he said it with some difficulty in that NBC interview - doubtless now knows that Camus insisted he was no existentialist but, in reality, an absurdist. He would thus have understood the phenomenon of America's 43rd president only too well, alas. But when the American electorate go to the polls on 7 November will they, too, finally have gained that same understanding?

Midterm runners: the ones to watch by Andrew Stephen

Harold Ford, Black, aged 36, photogenic, has been a Democrat Congressman for 12 years and now running for the Tennessee Senate seat of Bill Frist (who's leaving to gear up a doomed campaign for the presidency in 2008). If elected, he would be the first black to win a Tennessee Senate seat since the Confederacy. Currently running at 52 per cent but consensus is that he won't make it. If he does, it will be a bellwether triumph for the Democrats and indicate a rout of the Republicans.

Nancy Pelosi, 66, and the only woman on my list, House Democrat leader since 2003. Will safely win her House seat in California but if the Democrats take the House she will become Speaker (thus next in line for the presidency if Bush and Cheney should simultaneously fall under a bus). The Republicans (Newt Gingrich, for instance) are already trying to paint her as such a wild lefty bogeywoman that this is unthinkable. She is not a political rocket scientist so it will be interesting to see how she handles it all (and if she can).

Rick Santorum, 48, senator for Pennsylvania since 2000. Exceedingly ambitious and unpopular on both sides: ghastly, very right-wing, anti-gay, supposed "Christian". Will be targeted as bogeyman by the Democrats. Will probably again be a case of goodbye, Rick.

Joe Lieberman , We know all about him and why he will be running as an Independent in Connecticut. Currently neck-and-neck or slightly ahead in polls, but will public support pro-war Democrat-turned-Independent?

Chris Shays, Republican congressman for Connecticut since 1987, considered man of enormous integrity, principles, et cetera, et cetera and also quite well known. Supported Iraq war, now says it was wrong, and so is in trouble.

George Allen, 54, senator for Virginia and former Virginia governor - hot possible Republican candidate for the presidency in 2008, but could face a hard time in Virginia (down to 47 per cent in latest poll) and a defeat would pretty well mean the end of his hopes. Another possible symbolic bellwether case for the Republicans.

Conrad Burns, 71, Republican senator for Montana since 1988. Boring but heavily implicated (though not yet charged) in Abramoff scandals. Will voters care? Yes, very probably . . . and it will be farewell, Conrad.

J D Hayworth, colourful Republican congressman for Arizona since 1995, 48, on the telly (ie, FNC) a lot and therefore unusually well-known for a congressman - suddenly finding himself in trouble. Bellwether again.

Bush's book list
Research by Joshua Hergesheimer

This summer, the president's reading included:

The Outsider by Albert Camus

American Prometheus by Kai Bird and Martin Sherwin (a biog of Robert Oppenheimer, father of the atomic bomb)

Hamlet by Shakespeare plus two other "Shakespeares"

Books read since 2005 include:

Imperial Grunts: the American military on the ground by Robert Kaplan

When Trumpets Call: Theodore Roosevelt after the White House by Patricia O'Toole

Alexander the Great: the last great tsar by Edvard Radzinsky

Nine Parts of Desire: the hidden world of Islamic women by Geraldine Brooks

The Big Bam: the life and times of Babe Ruth by Leigh Montville

Salt: a world history by Mark Kurlansky