Why the Republican race is the saddest, dirtiest, lowest and most pitiful campaign I've ever reported on

Let's be clear. This is the saddest, dirtiest, lowest, and most pitiful political campaign I have ever reported on.

There was an Iraqi referendum I covered in October 1995 when Saddam Hussein "won" 99.99% of the vote. Perhaps that was more brutally cynical.

So let's put it another way: This contest for the Republican Party nomination is not worthy of America. In fact, not worthy of a third-rate authoritarian regime.

The recent parliamentary election in Iran, reported on so ably by my colleague Rageh Omaar, has been significantly more uplifting.

In the last 48 hours, as the Republican Party prepares to jump over the abyss in an embrace of Donald Trump, what has the debate been about?

Almost unbelievably, it's been an exchange of mocking personal abuse.

Rival Republican candidate Marco Rubio has accused Trump of having 'small hands' and 'spray tan'. Credit: Reuters

Rubio and Trump arguing over who sweats more; whether Trump will sue his tanner for the orange tint to his skin; whether one of them urinated at the podium during the last debate; even - forgive me for writing this - the size of Trump's...well, you get the picture.

His is not a nominating contest that is focusing on the anguish of Syria, the nightmare of almost daily mass shootings, or the challenge of confronting Russia in Europe or of China in the Pacific.

No, this is school-yard bullying and petty abuse.

Who would have thought that I must ponder whether to let my 13-year-old son listen to the Republican TV debates?

(I do let him, but then explain that this is not acceptable language for him to use - ever).

Tomorrow is likely to be a crucial day in deciding who emerges as the Republican nominee for the Presidency.

It is Super Tuesday, when eleven states vote simultaneously, awarding half the delegates needed to win the prize.

Ted Cruz and Marco Rubio - both young Senators, both Cuban-Americans - are the only serious contenders to stop Trump from a victory that would likely destroy the party and change American politics forever.

Donald Trump is hoping for a knock-out blow that will destroy both his rivals.

They will fight on whatever happens, because the stakes are so high.

But if Trump's angry coalition of the alienated is triumphant late on Tuesday night, then America will face a crisis.

A crisis in its politics and in how the world views the United States, certainly. But no less, a crisis in its culture and sense of identity.