With his latest batch of primary victories, Obama is looking increasingly unstoppable. This is faintly embarrassing for me, since in my last pronouncement on the US election I suggested that the racial polarisation of the electorate in South Carolina looked bad for him. Obviously - like many a pundit during this election - I spoke too soon.
But - to misquote John Kerry - I was right before I was wrong. The proof of this is sitting in a desk draw in my office. I put £10 on Obama to win the presidency at 7-1 last December. Not a bad bet, since he is now odds-on to be president with Ladbrokes.
What I failed to realise was that while voters in the South are dividing on racial lines, this is not true of the country as a whole. Chrystia Freeland offered an interesting explanation for why this might be in her FT column on Saturday, citing research that showed that Americans who live in largely white areas are likely to be more liberal on racial issues than people who live in mixed areas. Make of that what you will.
Even so, the trend could still be dangerous for Obama in a general election. A racially-divided southern electorate can carry him to victories in Democratic primaries, but might mean defeat all across the South in November - which would give John McCain quite a head start in the electoral college. On the other hand, the latest batch of primaries seem to show that he is beginning to pick up votes among groups that were formally fairly solid for Hillary - in particular, women and Hispanics. Maybe Obama really is unstoppable.