What makes this presidential election different from all other presidential elections? And different from what we expected when the year began?

First, neither party's presumptive nominee was chosen by massive support from primary voters, as John Kerry was in 2004, George W. Bush in 2000 or Bill Clinton in 1992.

That may not seem obvious in the case of John McCain, who effectively clinched the Republican nomination on Super Tuesday, Feb. 5. But look at the numbers: In January, McCain won New Hampshire 37 percent to 32 percent, South Carolina 33 to 30 percent and Florida 36 to 31 percent. On Super Tuesday, he won more than 50 percent only in states that were essentially uncontested: Connecticut, New York and New Jersey. He won Missouri by only 33 percent to 32 percent and California by only 42 percent to 35 percent, but won big delegate margins because of Republicans' winner-take-all rules.

McCain's strategy from July 2007 was to count on the other Republican candidates' strategies to fail. That was risky. But it worked. Republicans have accepted his victory because they're temperamentally inclined to fall in line and because it became obvious that he was the candidate with the best chance to win in the fall. But McCain was not really a consensus choice.

As for Barack Obama, at this writing he leads Hillary Clinton by 153 in "pledged delegates," those chosen in primaries and caucuses. But about 90 percent of this lead -- between 130 and 140 delegates -- came in caucuses, where the enthusiasm of his followers and the inexplicable failure of the Clinton campaign to mobilize hers gave him big victories.

We know from the nonbinding "beauty contest" primaries in Washington in February and in Nebraska on May 13 that Obama would have won much smaller margins in primaries in those states -- and much smaller delegate margins, thanks to the Democrats' proportional representation rules.

Democratic super-delegates, given votes in the 1980s to counterbalance the enthusiasm of left-wing caucus-goers, have instead moved toward ratifying the results of the caucuses and the paper-thin delegate edge Obama won in primary states. They may have good reasons for doing so -- fearing a Clinton loss in the general or a backlash from black voters if the first serious black candidate is rejected. But Obama, like McCain, is not the consensus choice of a large majority of Democratic primary voters.

This election is different from all others in another respect: These two presumptive nominees have no particular regional identity. John McCain was born in the Canal Zone, no longer a U.S. territory; grew up on military bases; moved to his wife's home state of Arizona and, running for Congress, noted accurately that he had lived in Hanoi longer than anywhere else.

Barack Obama grew up in Hawaii and lived for a time in Indonesia, went to school in Morningside Heights and Cambridge, and made his career in a city where he had never lived before, Chicago. He has been universally accepted by the Chicago political and fundraising establishment and won wide margins in Illinois. But neither he nor McCain has spent much of his life in ordinary Middle America.

Another way this election has been different from any other since 1960 is that neither money nor the thing it mostly buys -- television advertising -- has made much difference. Obama has been a prodigious fundraiser, raising unheard of sums over the Internet. But his money advantage didn't enable him to close the deal and beat Hillary Clinton in Ohio, Texas, Pennsylvania or Indiana.

Most of his delegate advantage, as noted, he owes to caucuses, in which money doesn't much matter. And if money mattered among Republicans, their nominee would have been Mitt Romney, who probably ran more TV ads than all his party rivals put together. Obama will massively outspend McCain from here on out, but that doesn't guarantee him victory.

Finally, this election has been different because the most tested candidates didn't run the best campaigns. John McCain, blooded in the 2000 race, depended on a strategy that left the initiative to others: It was always possible that one of his rivals would come up with a strategy that didn't fail.

Hillary Clinton, more than an interested observer of her husband's 1992 and 1996 campaigns, failed to organize the caucuses, ran out of money and made up stories of having been under sniper fire in Bosnia. Obama, the least experienced candidate, has clearly run the best campaign -- yet was unprepared for the exposure of his 20-year pastor and spiritual mentor the Rev. Jeremiah Wright.

This is a start on a list that may grow longer as the campaign goes on.