And then there were four and a half

Back at the end of April, when we looked at the Democratic field for next year’s United States presidential election, there were six clear front runners. With exactly three months to go until the first voting takes place – the Iowa caucuses – Beto O’Rourke has just become the first of those six to drop out.

The other five are well spread out. The three leaders are also the three oldest among them: former vice-president Joe Biden, Massachusetts senator Elizabeth Warren and Vermont senator Bernie Sanders.

Biden’s support has been fairly stable since mid-year, in the high 20s. Warren drew level with him a month or so ago, but has since eased back to around 20%, still well ahead of her mid-year position. Sanders has consistently polled in the high teens, although Warren’s rise means he has dropped from second to third. (RealClearPolitics compiles the polling data.)

From there it’s quite a gap to Pete Buttigieg, mayor of South Bend, Indiana, who’s sitting in the high single figures. Behind him, California senator Kamala Harris is just clinging to fifth place, and relevance, on about 5%.

Harris’s campaign started well, but her fall in the polls since July has been relentless. Unless she can do something to turn that around, and quickly, it seems almost certain that she will be the next of the leaders to drop out.

None of the others – and there are still another eight or ten semi-serious candidates – have made much impression. Businessman Andrew Yang and Minnesota senator Amy Klobuchar are at the front of the pack, but neither has been able to consistently score above 3%. There is still time for one of them to do something special, but you would have to bet against it.

Polls in Iowa roughly mirror the national ones, but with exaggerated movement. Warren’s rise there has been more sustained, to the point where she is now a clear leader. Biden and Sanders are virtually tied; Harris’s fall has been more dramatic, putting her now below Klobuchar. And Buttigieg’s rise has been much more pronounced, bringing him level with or perhaps slightly ahead of Biden and Sanders.

New Hampshire, which votes the following week, tells a similar story, although without Buttigieg’s meteoric rise. The noteworthy point there is the fact that Sanders can still only manage third place, despite the fact that he won it comfortably in 2016, beating Hillary Clinton by better than 60-40 (after Clinton had very narrowly won Iowa).

And although the differences between them are greater than might appear at first sight, there’s no doubt that Sanders voters are more likely to migrate to Warren than to Biden. So despite Biden’s lead in the national polls, it’s not hard to see why most pundits now treat Warren as the one to beat.

The betting markets agree; Sportsbet has her a strong favorite at 11-10 against, followed by Biden at 10-3, Buttigieg 7-1 and Sanders 8-1. Harris is way off the pace at 40-1; ahead of her is not only Yang at 14-1, but also Clinton, whom nostalgic punters have backed in to 12-1.

There seem to be two probable ways that this could play out. One is for Biden and Warren to fight out a series of close contests, with neither getting a big early advantage. In that event they would soak up most of the oxygen, making it difficult for any of the others to get much of a look in.

The other is for Warren to get Biden’s measure quickly and decisively, making her a clear front runner and inviting the younger candidates to target her.

But despite Buttigieg’s impressive numbers in Iowa, both he and Yang still look more like novelty candidates than serious presidential material. If Harris drops out, it’s hard to see where another viable contender is going to come from.