It seems to me the principal needs for a "coattails" political victory include: an overwhelmingly popular nominee, an overwhelmingly unpopular opponent, a historically significant novelty or potential realignment at play and, less interesting but most important, the attraction and activation of an enormous and motivated campaign machine.
Looking ahead to 2008, it's possible we could see a coattails effect on election night, especially in the case of one particular candidate, but given the close division of a 50-50 or 51-49 electorate, I doubt it.
Consider the factors one by one.
1. Overwhelmingly popular candidate. The partisan divide in the United States, a condition that can at times be both a blessing and a curse, means it's unlikely either party will nominate a candidate that huge numbers of the opposition will love.
There's no Dwight Eisenhower or Theodore Roosevelt in this bunch. True, Sen. John McCain (R-Ariz.) has always enjoyed a certain affection among moderate (and even some liberal) Democrats, but in the end, he's just another pro-life, pro-war conservative, and the Democrats flat-out don't agree with him.
Former New York Mayor Rudy Giuliani, if he could get nominated, would certainly garner a lot of support from Democrats, but it's just as likely he would lose at least one conservative for every liberal he gained. Given the current crop of candidates, there's no reason to predict a 55 percent popular landslide for any of them.
2. Overwhelmingly unpopular opponent. Republicans will certainly be hamstrung to one degree or another if President Bush's popularity remains as low as it's been this past year. Depending on how closely tied the Republican nominee is to the president, it could provide a real opportunity for the Democrats, but all the Republican candidates know this and are distancing themselves from the White House.
On the other hand, it's possible that, in the light of public scrutiny, Sen. Hillary Rodham Clinton (D-N.Y.) will prove unlikable. It's also true that Democrats -- even if they don't like her -- want to win and won't easily jump what they see as a very fast, strong ship.
3. Historically significant novelty. On the Democrat side, both Sen. Clinton and Sen. Barack Obama (Ill.) offer historical novelties, as potentially the first woman and first black president. Of the two, I think Sen. Obama has the much greater claim to significance.
Mrs. Clinton, after all, has already been at the highest levels of the executive branch, for all intents and purposes, and foreign leaders like Golda Meir, Indira Gandhi and especially Margaret Thatcher have removed much of the novelty of a woman president for most Americans. Obama's another story. It would be a unique thing, a black man leading an overwhelmingly non-black country.
Though his campaign has smacked of amateurism, if he can get himself nominated, there's no telling how much novelty-based positive media coverage he'd get or how much that could impact down-ballot races.
4. Potential realignment. Unlikely. Liberals are as liberal as ever and aren't likely to suddenly shift political allegiance in the middle of a war they despise. Circumstances change, of course, but there's nothing in the cards now to suggest large numbers of liberals or conservatives will change their worldviews.
5. Massive, motivated organization. Here is the first case where there is a clear winner: Hillary Rodham Clinton. The George Soros-funded, Harold Ickes-led shadow party is probably already large enough and well-enough organized to elect Mrs. Clinton as it is -- and she hasn't even locked up the official Democratic National Committee infrastructure yet.
Effectively, Mrs. Clinton is going to have two national organizations working to elect her, under the banner of a furious party that simply cannot contemplate four more years out of power. Add in the continuing failure of even relatively popular Republicans to raise money and the current Republican field's lack of a slam-dunk front-runner, and it's hard not to conclude that if and when Democrats unite behind Hillary, that machine is going to be awfully tough to beat.
Again, it's unlikely Sen. Clinton's coattails will be very long, seeing as she's so unpopular among Republicans and right-leaning independents, but that organization of hers is the closest thing in the 2008 race to a real chance at a national landslide.