BEFORE last night's Obama/ Romney debate the American political rulebook said that debates do not swing elections.
While the debates can give a candidate a short term bounce, the trend after the debates tends to be the same as the trend before them.
Without a doubt Romney had a good night. But nothing happened in Denver to change the political rulebook. While commentators, especially the network television ones, like to think that TV debates swing elections, the reality is that they haven't.
Yes, there have been some incidents like President Bush Sr's constant looking at his watch at the 1992 debate or President Ford's assertion in 1976 against Jimmy Carter that eastern Europe was not dominated by the USSR, but none of these ever reversed the course of the elections.
Bush Sr had started to lose ground to Clinton before the debate. Ford was trailing Carter badly by the time they debated. Indeed Ford only agreed to the debate because he was behind. Though we think these to be the norm in the US since the famous Nixon/Kennedy debates of 1960, the 1976 Carter/ Ford one was the first in 16 years.
Presidential debates by their nature tend to favour the challenger. The format raises the challenger's status presenting the two candidates as equals.
The challenger can put the President on the back foot by going on the attack and picking apart the incumbent's record.
That is what Romney did last night, and he did it effectively.
While the current race is relatively tight, the polls have favoured Obama since before the summer. As with Carter in 1980, the Democrats should be in trouble. Polling suggests that Americans believe their country is on the wrong track by a margin of almost 20pc. Optimism is on the decline. Only 43pc of middle class Americans expect that their children's standard of living will be better than their own. This compares to 51pc four years ago.
These numbers should be poison for Obama and the Democrats and make the election a slam dunk for the Republicans, except the same Americans either don't understand or believe the alternative vision offered by Romney. His people know this. He went into last night's debate with a mission to change American's views of him. He did himself some good in that regard. He not only went on the attack on Obama's record, he also scored several points in denying the Democrats portrayal of him as a tax cutter for the rich. The issue for him is that he did this at the expense of discussing the details of his alternative.
Perhaps his position behind Obama convinced him he had nothing to lose with this approach, but the other risk for Romney is that his lurch to the centre may mean leaving some right wing voters at home?
In contrast, Obama seemed aloof and remote.
He was reluctant to attack and take Romney on directly. This may have been a deliberate tactic. His people may have felt that scrapping and politicking with Romney wouldn't look Presidential -- he never mentioned Romney's 47pc remarks -- however, it meant that he allowed several very answerable attacks on his record go unchallenged.
While Romney didn't land a knock-out blow, he did win in terms of punches landed. He also did well in terms of appearance and body language, he dominated the debate. These things matter. This is television after all. We get as much information from what we see as what we hear.
Arguably the real impact these debates will have will be down to the clips the TV news shows choose to use in the coming days, though neither man gave a hostage to fortune. The late night comics will have fun with Romney's threat to cut public funding for PBS and Big Bird, but I don't see last night's rather boring exchanges as switching anyone's vote.
Romney may have won the debate -- but I reckon he will still lose the election.