KEY POINTS:
A phone is ringing in the White House at 3am, who do you want to take the call? American political advertising can be incisive.
The Clinton message, voiced over a darkened image of a parent looking into a room of sleeping children while a distant, insistent telephone went unanswered, played on Texas television last weekend. It is getting credit for the late swing to Hillary that gave her the result she needed.
But I thought Barack Obama's response even better.
When the phone rang for the Senate vote on Iraq, he replied, Mrs Clinton made the wrong call.
This is more than a fascinating election, it's a joy to observe because all the serious candidates left in the race seem admirable in their own way. That may change now that Hillary has survived and will play rough to win. But the politics of mutual respect has been a rare treat.
I wonder if we could do it this year. We have two very respectable candidates for Prime Minister. Neither is perfect of course; nobody is. Helen Clark has her demons and deficiencies but on balance she has been an astonishingly good Prime Minister, her judgment consistently sound, her comments invariably sensible and informative.
John Key's weakness was exposed this week by the Government's move against the Canadian bid for Auckland Airport but he has leadership qualities that have been confirmed by critical scrutiny of his previous business career.
Like Key, Obama lost some of his gloss in battle this week. But if both are elected later this year our fate would be in good hands.
Happily, that can be said with even greater certainty if Americans, against all odds, elect the Republican nominee in November.
I watched John McCain on television when he clinched the nomination in Texas this week and it struck me that he offers something Clinton and Obama do not.
They promise "change", by which they mean more than a change of party in power but possibly not much more than a change of the race or gender of the President.
Ignore their faces, listen to their rhetoric, and you hear fairly standard policy speak from Clinton and great oratory - but only oratory - from Obama.
Listen to McCain and you might wonder whether he is a politician at all. Open your eyes and the impression is confirmed. He fails all the superficial tests of US politics. He looks old, sounds soft, dresses badly, grins like a chump. And his speeches are modest, reasonable, almost self-effacing but firm and clear in commitments that are not necessarily popular.
He will never match Obama on the stump or Clinton in television debate. In the early primary contests he was beaten for style and rhetoric by his nearest rival, former Massachusetts governor Mitt Romney, a candidate from central casting who readily reversed his liberal state positions for a national electorate.
The rest of the Republican field rounded on McCain for a bill he sponsored with Ted Kennedy that would have given illegal immigrants rights to services such as education for their children while strengthening the border against further entry.
His opponents called it an amnesty for illegals but the voters of New Hampshire forgave him. After that primary, he never looked back.
In Michigan where the depressed car industry has left high unemployment, McCain alone had the courage to tell audiences, "the old jobs are not coming back".
He believes in free trade which is reason alone to pray for his victory, especially when Clinton and Obama are playing up fears and suspicion of foreign competition and corporate behaviour.
They don't mean it; trade fear is standard feed for the Democrat Party base who vote in primaries. Obama and Clinton have shown themselves to be conventional politicians in that sense, while McCain has stood up to a pounding from his party's conservative core.
In a direct contest with Obama he would have to defend the invasion of Iraq, which he supported in the Senate though urging a stronger force level from the outset.
But I doubt the Vietnam veteran would have started a war to change the Iraq regime. With his war record, modesty, maturity and judgment he could not be more different from George W. Bush.
In any case, the important issue now is how to get out, and McCain sounds the more responsible than Obama on that score.
In substance his campaign has been more refreshing than Clinton's or Obama's. He has proved that people respect politicians who do not always tell them what they want to hear. John Key had an opportunity to do that when the Government interfered in the decision of shareholders in Auckland Airport.
Maybe Key will find the courage of McCain, especially now that America's next President might not be a woman or an African-American, unfortunately, but a man with nothing going for him, except integrity.
