Iowa caucus: Marco Rubio's performance is good news for America

Mr Rubio came close to relegating Donald Trump to what would have been a humiliating third place

Marco Rubio is seen by many as being the most electable Republican candidate (Getty)

The Iowa caucuses, the kick-off event of the US presidential primary season, have revealed much but settled nothing.

On the Republican side, they have shown that Donald Trump is not invincible. They have confirmed Ted Cruz’s organisational strengths, and his appeal to religious and social conservatives. Most important, they have clearly signalled that Marco Rubio is the strongest contender in the so-called “establishment lane”.

Mr Rubio came close to relegating Mr Trump to what would have been a humiliating third place. A repeat performance in New Hampshire next week, and the Republican contest will surely be a three-horse race, between Messrs Cruz, Trump and Rubio. The surge of the young Florida senator in the final days of campaigning reflected a belief among voters that he is the most electable candidate, and the one most capable of unifying a deeply divided party.

Despite his victory, Mr Cruz is detested in the upper reaches of the party and shows no sign of being that person. As for Mr Trump, how that prince of bombast, braggadocio and the gratuitous insult will respond to actually losing will be among the most fascinating questions of the frantic weeks ahead. But he has touched a powerful nerve in the electorate, and will surely remain a factor. The Trump bubble has been deflated. It has not burst.

On the Democratic side, by contrast, Iowa has not greatly changed matters. Everyone knew the contest between Hillary Clinton and Bernie Sanders would be close, and it was.

Mr Sanders, with his appeal to the young, the liberal elite and independents, seems set to win in New Hampshire next week. Ms Clinton has a fight on her hands. But that does not alter the likelihood that she will ultimately prevail, once the race moves into states that better reflect the ethnic and cultural diversity of the Democratic Party.