Yesterday, Obama did something he's never really done before: he staked out a clear position to the left of centre and said to the Republicans, 'Come and have a go if you think you're hard enough.' Up until now, he's been so keen to be reasonable that he has, to paraphrase George Bush, 'negotiated with himself', coming to the table with proposals that are already close to the Republican position. The Republicans then reject them for being too left wing or wrench them further to the right. The end results is that, even to the uninvolved spectator of politics, the president comes off looking weak and impotent.
This time, he's decided to draw a clear contrast with the right: tax raises on the rich vs deeper cuts to Medicare and social security. He'll probably end up in the middle - in fact, that's where he should end up, if he wants to win in 2012. But he's betting that the best way to get there is via the left. It's a big bet. The danger is that even though the policies he laid out are, on their own terms, popular, the signal they send about his position is that he's a traditional tax and spend Democrat. During the British 2005 general election the Tories took a hardline on immigration because polls told them it was a popular position. But the signal it sent was 'same old Tories'.
Much will depend on how Obama communicates his proposals. Yesterday's performance was feisty and energetic, for him, which is good - he can't afford to come across as passive right now. But he walks a fine line. The danger is that the more he talks about 'fairness' the more left-wing he sounds. The focus of his message needs to be on paying down the deficit.
The worst possibility, for Obama, is that it doesn't matter what he says. The credibility of politicians follows something like Hooke's Law - it is elastic, but it has a limit. Politicians can mess up, and recover their credibility, and if they're good they can do so more than once. But at a certain point, voters just lose faith altogether - the spring is broken. Obama must pray that hasn't happened yet. If it has, it doesn't matter what he says - nobody will be listening.