KEY POINTS:
The first decision made by a nominee for President of the United States is normally the least important. The selection of a running mate, who in the event of victory would be Vice-President, attracts much discussion before the choice is made but not much afterwards. That may be true of the Democratic Party's ticket this year but not of the Republicans'.
The choice made by the Republican nominee, John McCain, is more important than normal for one reason: Mr McCain is 72. If he wins in November he will be the country's oldest President at the time of taking office. His age is the main drawback of his campaign. While he seems fit and there is no reason to think he would not see out a four-year term, he needed to offer voters a potential second President.
He has not done so. His choice of little known Alaska Governor Sarah Palin may have been made for many reasons but they do not include her preparedness to be President if need be.
He chose her, no doubt, because, first, she is a woman, second, she is young and third, she is not as liberal as him. As a woman she might, he hopes, draw voters disappointed by the Democrats' failure to select Hillary Clinton. At age 44, Mrs Palin is even younger than Mr McCain's opponent, Barack Obama. As a social conservative - against abortion, gay marriage and the like - she might reconcile the religious right to Mr McCain's candidacy.
Only the last hope seems realistic. The first seems not just futile but insulting to the voters it seeks. It implies that those excited by Mrs Clinton's candidacy would put any woman in the White House, or near it - the Republicans are offering second best. The Democrats gave a woman, Geraldine Ferraro, second place on their ticket in 1984 and it made little difference to Walter Mondale's prospects against the incumbent, Ronald Reagan.
If Mr McCain was hoping that Mrs Palin's presence would deprive his rival of an age advantage, it may have done exactly the reverse. With his choice of running mate he has deprived himself of the argument that Mr Obama is too young and unprepared for the office he seeks. Beside Mrs Palin the senator from Illinois looks well qualified. As a second-term governor she comes from an executive role, whereas Mr Obama's elected positions have been entirely legislative. But Alaska's population is no larger than Auckland's; she would need to hold her state a while longer to have a credible springboard to Washington.
Neither presidential candidate appears to have chosen his running mate well. Mr Obama opted for a Senate colleague, Joe Biden, who contributes some experience to the Democrat ticket but he is not the respected figure the young candidate possibly needs. Mr Biden, something of a maverick by reputation, looks to be the kind of Vice-President who would happily preside over the Senate but be given little else to do in an Obama Administration.
He would be in good historical company. Most of those who have been "a heartbeat away" from the presidency might as well have been in another country. Frequently they were; attending foreign funerals is one of the classic assignments of the office.
But often enough, too, fate has called them to the highest office. Presidents Truman, Johnson and Ford came to power on their predecessors' death, assassination and resignation respectively. Candidates probably do not want to contemplate those possibilities when it comes to selecting a running mate, but they must expect voters to look at their choice in that light. Mr McCain could have made a more responsible decision. This one may cost him more than he stands to gain.
