A close and bitter US presidential election will be decided today

The United States seems as bitterly divided as it has ever been.

Hillary Clinton, the Democratic Party nominee for president, and Donald Trump, the Republican Party candidate, provoke feelings of deep hostility among followers of the other.

Mrs Clinton, although admired for her long experience of politics and government, is never a figure to whom the American public has warmed. Yet her husband was adored by Americans, and consistently among the highest approval ratings of any of the 44 presidents, even after the bid to impeach him.

Mr Trump was a celebrity for years, first as a tycoon with a high profile and an ostentatiously glamorous life, and then as host of the American version of the TV show The Apprentice.

But since his emergence first as a wildcard contender for the Republican Party nomination, Mr Trump has built up a large and powerful number of critics and enemies. His extraordinary bluntness and often offensive comments have contributed to negative ratings so high that he ought in theory to have no chance of success today.

And yet he is so narrowly behind Mrs Clinton in the polls that he might just pull it off. His enduring success shows the depth of alienation that many Americans feel from the status quo.

On grounds of experience Mrs Clinton is by far the more eligible candidate. But her liberal views are anathema even to the many conservatives who are wary of Mr Trump.

Unionists in Northern Ireland understand this: the Democratic Party once seemed ambivalent about IRA terror (the party’s view of the situation here is more nuanced now).

The decision today is one for the Americans. They will not welcome outside advice, in the same way that Britons spurned Barack Obama’s warning on Brexit.

If things turn out well, the winner tomorrow, whoever it is, will work hard to be a healing figure and show competence in the most important political job in the world.