Nick Clegg won last night's leaders' debate in the snap opinion polls: the front pages of the newspapers show this is easily the best day's press coverage the Liberal Democrat party has ever had in its 22 year history.
The impact of the debate may well be somewhat overstated in the next couple of days. We will see a significant morale boost to LibDem campaigners. The increased salience of the third party will affect how the media cover the election, for at least 48 hours or so. By next Monday, I would be surprised if many voters can remember much from the debate beyond general impressions, or if the voting intention shares in the polls shows any sustained shift attributable to the debates. Clegg should get a boost in his leader approval ratings, but probably a smaller one in the 'who is best choice for PM' stakes. That is a different question from 'who did best in the debate' and one where the suspension of disbelief remains an issue for the third party.
In the last big European General Election in Germany last Autumn, the sole leaders' debate saw the SPD's Frank Walter Steinmeier win a clear points victory over Angela Merkel: that boosted SPD morale but did less to affect the votes. (The FDP, Greens and Left Party took part in a separate debate of the smaller parties rather than debating the big two).
In place of a detailed review, I feel happy after the event to stick by my prediction that all three leaders would do perform fairly well, and Clegg best, though I expected Cameron to do somewhat more to impose himself than he did this first time around.
Still, I think there are three ways the debate may influence the next phase of the campaign:
Firstly, the debates will be one of the most important tools for a slice of the electorate in making up their mind, and so a significant chunk of voters should at least bring the third party into consideration when they might not have done before.
Secondly, how does the increased salience of the third party affect campaign strategies? Perhaps the Conservatives need to think carefully about their tactical response. We might expect increased Tory-LibDem antagonism in the week ahead, as the Torises attempt a classic LibDem squeeze and suggest that a vote for Clegg will keep Brown in. But too aggressive a response could help the LibDems - suggesting they are a threat, and risks positioning the Tories as status quo defenders of politics. And it will help Gordon Brown's strategy of seeking to make the next two debates more often two on one against the Conservatives, than two on one against Labour. So the Conservatives will want to get back to a straight Tory-Labour argument. Labour may be, overall, rather happier with a three-party frame where it focuses its own fire to the right.
Thirdly, I think the big opportunity for Clegg may be this: the last week of this campaign it is likely that the Conservatives and the media will make the threat of a hung parliament - instability and financial meltdown - a major theme.
Whether the instability threat is convincing depends on the level of public confidence in how the smaller parties would approach that scenario. If Clegg continues to do well in the debates - and is thought by a large portion of the electorate to be fresh, sensible and worth listening to - this may be more difficult.
A Times poll this week found angry voters would prefer a hung parliament. Clegg's argument should be that Britain has nothing to fear from that democratic outcome: that if voters don't want one party to have all of the power, we should have a politics sensible enough to deal with that and get on with making it work.
But that involves a tricky inside/outside balancing act for the third party too. Clegg often sought to pitch a populist outsider 'plague on both your houses' argument. But making the case for a 'balanced Parliament' effective also depends on showing that he could work constructively, inside the system, with the other parties. So his offer of a tripartisan engagement on both spending and social care was both sensible.
Indeed, perhaps the secret of Clegg's appeal last night was that the outsider rhetoric was combined with an approach of choosing not to articulate major differences on several policy issues. Clegg did not sound particularly distinctive or especially liberal on either immigration or crime: for example, highlighting his regional restrictions on work permits not mentioning his "let them pay taxes" regularisation of long-term immigrants without legal status. He did emphasise the differences on Trident, which will appeal to a slice of the electorate - and I am not convinced that attacking the third party on that issue is going to pay many electoral dividends