WASHINGTON -- If you think this has been a strange campaign for president, you're right -- and not just because of the accusations of sexual harassment aimed at Herman Cain in recent days or cable chatter about Rick Perry's caffeinated speech in New Hampshire a week ago.
In five ways that have nothing to do with those developments, the Republican race is breaking with patterns of the past.
The first goes back to the beginning. This is one of the latest-starting, slowest-developing and most changeable nomination battles in modern memory.
In the previous campaign, John McCain filed his papers with the Federal Election Commission days after the 2006 midterms.
At least two Democrats announced before the end of the year. Mitt Romney was in shortly after New Year's Day 2007, and Barack Obama and Hillary Clinton were up and running in January 2007.
This time around, the candidates strolled rather than sprang to the starting gate.
Romney didn't file his papers until spring. Newt Gingrich had made several false starts toward filing by then, but did not finally become a candidate until later in the spring. Cain formally joined in May, Michele Bachmann and Jon Huntsman in June. Perry didn't announce until August, in Charleston.
That hesitancy fed the second difference between campaign 2012 and others. This year's contest also has been notable for the number of prominent Republicans who talked about running but who ultimately chose not to.
They include Mike Huckabee, Donald Trump, Mitch Daniels, Haley Barbour, Jeb Bush, Sarah Palin and Chris Christie.
And it isn't just that some big names didn't run. The attention paid to the non-candidates overshadowed and diminished those who were in the race.
That illustrates the third big difference. In this nomination battle, there really hasn't been a dominant front-runner, as there has been in the past. Romney is generally described as the front-runner and has been from the start.
But some months ago the Gallup organization described him as one of the weakest front-runners in the modern history of Republican races, given that he has been stuck or stable in the polls at about 25 percent.
More telling, perhaps, is the fact that seven people have had a share of the lead in the Republican race at some point this year in one or more polls. Seven! They are Romney, Huckabee, Trump, Palin, Rudy Giuliani, Perry and Cain. Has there ever been a more fluid race or a more unpredictable GOP electorate?
The fourth big difference is in the way candidates are running their campaigns, based on traditional measurements of activity.
Start with fundraising. At the end of the third quarter in 2007, Republican candidates collectively had raised about $230 million. This year, the field has raised just $85 million. Everyone says fundraising is more difficult this year. There is the proof.
That brings us to the fifth and most important difference. Republicans are engaged in a national campaign, one that has played out less in living rooms in Iowa or town halls in New Hampshire and more on debate stages in those and other states, on prime time and Sunday morning shows and through cable commentary, blog posts and tweets.
Debates have shaped and reshaped the field, and are likely to produce more changes before the New Year arrives and the primaries and caucuses begin. Social media may be playing more of a role than anyone knows in organizing efforts, but no one can tell that yet.
Whether all this is an aberration or the new normal, no one knows.