By James Landale
Deputy political editor, BBC News
Ten days in and the election is poised. The Conservatives are ahead in the polls, but not far enough to ensure a majority.
The campaign has been dominated by a narrow discussion about National Insurance.
The manifestos have come and gone and left the nation largely unmoved.
The politicians are desperate to find a way to engage the electorate.
Enter the television debates, studio left.
For the broadcasters, this is an exciting moment - an historic change that gives them a new toy to play with.
For the bloggers and tweeters, there is a wealth of new trivia about which they can obsess - the format, the spin rooms, the who-won-what-with-the-best-line post-match analysis.
But for the election, the importance is straightforward and obvious.
These debates will be watched by millions of voters. The leaders of the three largest parties will be exposed to four-and-a-half hours of close scrutiny.
For the many voters who have yet to make up their minds, these debates could help shape their final decision.
In other words, a little bit of telly over three Thursday evenings could transform a relatively open election in a way that - so far - nothing else has done.
The debates are a delightful uncertainty in a three-week grid of controlled political performance that is often as boring as it is uninsightful.
Certainly, the three parties believe the debates could prove decisive.
Not for nothing have they set aside a huge amount of time for Messrs Brown, Cameron and Clegg to prepare.
American and other debate experts have been drafted in. All possibilities in such an unpredictable format are being anticipated. All sides are doing their best to manage expectations, downplaying their man's chances while egging up their opponents'.
For Gordon Brown, the debates are an opportunity to show that after 13 years in power, he has something left to offer the electorate.
He can use them to show his experience and knowledge of government. The danger is that he looks like a tired incumbent, worn down by years in office, uninspiring next to his younger opponents.
For David Cameron, the debates are an opportunity to convince voters they can trust him to be prime minister.
The polls suggest that some people doubt the Tories' competence. The debates give Mr Cameron the chance to offer reassurance to these voters.
The danger is that he comes across as less than prime ministerial next to the current incumbent, a callow young pretender not quite ready for office.
For Nick Clegg, the debates are a heaven-sent opportunity, never before granted to a Liberal Democrat leader, simply to put his face before the nation.
For him, the debates are about exposure, exposure, exposure. These three programmes are worth millions of pounds in leaflets, videos, adverts, booklets, manifestos and the other paraphernalia of campaigning.
The Lib Dems will get their message direct to an electorate whose consciousness may not yet have been troubled by the existence of N Clegg.
The danger is that voters spend the evening staring at the telly watching the debate thinking: "Who the hell is that bloke standing on the left?"
So how might the debates change the dynamic?
1. The gaffe. One of the contenders could say something stupid or inaccurate. They could misspeak, get into a muddle and leave themselves looking incompetent and not up to the job.
2. The reaction shot. In television debates, the camera is always on. One of the contenders could scratch their nose, look at their watch, sneer, sweat or blush in a way that makes them look aloof or unengaged. There is a real art in remaining still and appearing to be interested in what other people are saying. An angry Gordon Brown glower or an irritated David Cameron blush could reveal much.
3. The positioning. In a three way debate, one of the candidates could be ignored and squeezed out of the discussion. This is the risk for Nick Clegg. He could be left looking like a spare part while Messrs Brown and Cameron go at each other. Alternatively, the positioning could allow two contenders to gang up on the third. This is the danger for David Cameron.
4. The line. A well-chosen, well-timed gag or remark can transform a debate, particularly if it highlights an opponent's weakness or a candidate's strength. The risk is that it looks cheesy or pre-cooked. When voters are desperate for authenticity, they might prefer genuine passion to clumsy artifice. But in these debates the audience has been banned from making any response - there will be no Question Time booing or snorting - so the key bon mot might be harder to identify.
5. The detail. Political debates require facts and figures, but not shopping lists. If Gordon Brown provides a Budget-style shopping list of micro-detail, he will suffer. As the Tory commentator Danny Finkelstein once said, this is an election not an edition of Mastermind.
6. The body language. The man who looks most at ease, most confident, most engaging, most likeable and most statesmanlike will do well. Anyone who looks awkward and inauthentic will not.
7. The attack. A well-aimed, elegant, humorous skewer that goes with a grain of truth is more effective than a cheap insult that will turn off voters already disillusioned with politics. Anyone who goes for the gutter could well stay there. Too much parliamentary knockabout will lose votes, not gain them.
Whatever happens, the impact will not come just from the fact that millions have watched the debate. It will come also from the fact that the mistake or winning line will be amplified as it is repeated endlessly across all media, reinforcing the message for good or ill.
This is the holy grail for the parties or the political hell their spin doctors do not countenance even in their nightmares.
Of course, the debates could change nothing. They could be 90 minutes of dull telly, a cautious recitation of soundbites and slogans from men more fearful of making a mistake than having the courage to take a risk.
They could simply confirm voters' views and prejudices about the candidates and make no real difference to the outcome of the election.
But equally they could be a fascinating glimpse into the characters of the men who would be our prime minister, a window into what they really believe and think, moments of genuinely democratic television that help make up the minds of a nation that is still working out what to think.