November's race for the White House could rest with the popularity of the vice-presidential candidates.
The floor of the Senate is a decorous place. It is cool and marbled and hushed.
Senators in the American system are so independent of party and so grand - with their staffs and their suites of offices - that it is unusual for them to clash, at least in the British parliamentary sense.
When an extreme difference of opinion is unavoidable, a senator might say that his colleague - though a man of integrity and grit and fundamental goodness - has on this occasion been poorly advised.
George Bush has Dick Cheney's political experience behind him
So there was some raising of eyebrows when the Vice-President, Dick Cheney, strode across the Senate floor and told a Democrat to "Fuck yourself".
Mr Cheney is widely believed to have lost the plot in recent months.
He is a man capable of genuine self-effacing humour, particularly about his health problems.
He does not receive messages from God - at least not ones he talks about - which gives him a reassuringly rational air in an administration which has more than a tinge of zealotry at its core.
But Mr Cheney is cross.
He has taken the rap for the mess in Iraq; taken the rap for the absence of weapons of mass destruction; taken the rap for the impressive sums of money being paid to his old company Halliburton for its part in supplying the troops.
And he is, it seems, heartily sick of it all. Sick enough, the Democrats hope, to fall apart on 5 October.
That is the date on which in Cleveland, Ohio, the vice-president - elderly, bald, ill, cross Dick Cheney - will debate with the Democratic challenger for his position - the youthful, tousle-haired, healthy, radiantly happy John Edwards.
It will be the most captivating clash in vice-presidential history.
The Democrats are salivating at the prospect of their bright young thing running rings around the crosser, older man until the vice-president lets forth a stream of obscenities and walks off the stage.
Mr Edwards is certainly an operator - a piece of work.
I watched him at close quarters this week and found myself on several occasions looking around at people, expecting them to be mildly embarrassed by the banality of the message they were meant to be imbibing, only to find them deliriously drinking it down and calling out for more.
For instance, in his first appearance with Senator Kerry - families draped attractively around them - Senator Edwards actually said that in the mill town where he grew up, people like John Kerry were the kind of fellows they used to look at and respect.
John Edwards lends flair to John Kerry's campaign
Senator Kerry - fresh out of Swiss finishing school and Yale, fluent in foreign languages - was he really a role model in rural North Carolina?
I don't think so.
Then again, later in the day, I heard the grinning Mr Edwards tell a crowd: "I'm here because I love America."
Now there's a lot of "loving America" in US political discourse - you get used to it after a while - and it's usually the warm-up message for something just a teensy bit more substantive.
But with Mr Edwards it is the message. That's it. He loves America and he smiles.
He was once poor. Now he's not.
He once believed that John Kerry was a verbose, stuck-up snob. Now he doesn't.
It's giddy-making stuff. It either turns you on or horrifies you, and most Americans, it seems, are - at the moment - in the first camp.
Does it matter, though, what people think?
The vice-presidential post was famously described once as being worth no more than a pitcher of warm spit.
Some vice-presidential candidates have been singularly useless. Remember Dan Quayle.
But hold on a second. Quayle won. Lloyd Bentsen crushed him in debate and the American people regarded him as a ridiculous choice, but he and George Bush Senior were sent to the White House anyway.
This year, though, it could be different. First: the electorate is evenly split on Mr Bush and Mr Kerry - half like one, half like the other.
Their running mate choice could swing the few hundred votes needed for victory.
Added to that, this year both the main contenders have reasons to depend much more heavily on their number twos.
Mr Bush needs Dick Cheney for ballast and experience. Mr Kerry needs John Edwards for flair and sex appeal.
So, uniquely in modern American history, the 2004 election could be won by the winner of the B-team contest.
It's not quite Cheney/Bush against Edwards/Kerry - but this is a big year for junior partners.
A lot is riding on Mr Cheney's control of his temper and Mr Edwards' control of his smile.
From Our Own Correspondent was broadcast on Saturday, 10 July, 2004 at 1130 BST on BBC Radio 4. Please check the programme schedules for World Service transmission times.