The 2012 presidential race is on. Kinda.

At the moment, it feels more like a wade through treacle - so slow is the pace of President Barack Obama's opponents. Mr Obama can be unambiguous that he is going to run because they are all showing varying degrees of hesitancy.

If the president is to get back into the White House he has to leap a number of obstacles: an economy that is so sluggish that there are constant worries it could go backwards and supporters who may be unenthusiastic about sending more troops to Afghanistan, bombing Libya and failing to close Guantanamo Bay prison. There is also huge uncertainly in the country about health care and much more we will be looking at in detail.

But the strength of opposition doesn't seem, at the moment, a particularly high hurdle. To British eyes, the primary system is one of the most curious parts of American politics.

The elite of British political parties have only grudgingly and slowly given the power of choosing their own leader. The principle of "one member, one vote" has been slow in coming.

Elections for leaders rarely grip in the same way as American internal elections. While any American can easily register as a Republican or Democrat and have their say about who represents them, in Britain being a party member still seems an effort of will.

Twenty-five pounds ($40) per year may not be much to play your part in conservative politics in Britain, £12 may be a bargain to have a say in the Lib Dems and it's only a penny (for those under 27) to join the Labour Party - but it still costs something.

There's a feeling that being interested in who becomes your PM or MP isn't enough. You have to be willing to sit in draughty village halls on wet Wednesdays listening.

The biggest difference is perhaps not in just who is involved, but how late in the political cycle the choice is made. This has a real impact. Every party leader, good or bad, has an image, policy likes and dislikes and personal ticks that colour voters approach to the parties as a whole.

The British public has years to get to know Ed Miliband and decide what to think about him leading a Labour government. Here in the US, the opposition is currently either faceless or hydra-headed. There is no obvious front-runner, and any prediction about who will be the Republican candidate in 2012 is nothing more than an informed guess.

Mr Obama v Michele Bachmann would be quite a different contest to Mr Obama v John Huntsman.

Republicans get to choose, late in the day, exactly what they want their party to stand for.

The influence of the Tea Party suggests any candidate will be economically conservative, but beyond that, it is impossible to predict very much. The candidates are so unenthusiastic about firing the starting gun, the first big debate at the Reagan library in California has been put back from next month to the autumn.

Mitt Romney, Tim Pawlenty, Newt Gingrich, Michele Bachmann and Donald Trump seem almost certain to have a go. Sarah Palin, Mike Huckabee, John Huntsman and Mitch Daniels seem less sure bets. And, of course, there are plenty of other names out there.

Mr Obama is starting the race now to make sure that whoever challenges him, his organisation will be ramped up and ready, with big bucks at its command.