The most critical election ever held in any democracy was the American presidential election of 1860, when the angry nation broke into warring camps that wrecked the country then and continue to bedevil us now. Because it is early in another presidential cycle that is strikingly similar — an enraged electorate, a looming war for survival, two generations of inferior politicians and their grandiose manipulations, a vain media — it is useful to look at the 2008 field of candidates in light of what happened 15 decades ago as the Republicans discovered Abraham Lincoln and the Democrats self-destructed.

Is it possible that the election of 2008 could bring a civil war that destroys the union, leaves 30% of the population hopeless, and puts America’s fate into the hands of hostile powers? Yes.

John McCain of Arizona and Hillary Clinton of New York are twin champions who dominate their respective presidential nomination races. Both are well known, well financed, well advised, tireless, and larger than life. Both represent a foggy middle ground of the nasty debates of recent decades. Mr. McCain is not as conservative as the vigorous Republican right wing demands, and for this he is despised by the clique called “true conservatives.” Mrs. Clinton is not as progressive as the ascendant Democratic left wing demands, and for this she is decried as unreliable by the clique called the “netroots.”

Significantly, months and even weeks before the 1860 nomination conventions, two gifted senators, William Seward, a Republican of New York, and Stephen Douglas, a Democrat of Illinois, dominated their respective party’s opinions in the same fashion as do Mr. McCain and Mrs. Clinton. America’s editors regarded Senators Seward and Douglas to be the guaranteed choices for the presidential contest, because of their genius and celebrity, just as Mr. McCain and Mrs. Clinton are the idols of all the major pundits today.

Nevertheless, Seward was bypassed, on the third ballot of the convention in Chicago, for the much less accomplished Abraham Lincoln of Illinois. Meanwhile, Douglas was backstabbed by his own party’s Southern faction, who walked out of the Democratic convention in Charleston to nominate their own candidate, the vice president, John Breckinridge of Kentucky, to stand for slavery and rebellion. In more confusion, the weak-kneed moderates in all camps assembled a fourth ticket that endorsed the Constitution but avoided the issue of slavery. Election Day in 1860, making Lincoln a minority president, was the beginning of the disunion that would curse the nation for the next 100 years.

Could this factionalism happen again? The Republicans today have two Lincoln-like candidates in the colorful Rudy Giuliani of New York and the colorless Mitt Romney of Massachusetts. Like Lincoln, Messrs. Giuliani and Romney have the advantages of coming late to the national argument: They have no voting record in Washington to burden them; their positions on the great issues of the day — war, peace, tolerance — are vague and anecdotal, and they strike everyone at first as parochial, underweight. The Republicans of 1860 chose the untested Lincoln just because the strongest candidate, Seward, could not unite the party. Lincoln was a compromise of compromises who, it was believed, would be credible against the expected opponent Douglas. Certainly Messrs. Giuliani and Romney could be expected to tangle with Mrs. Clinton with the same drama as Samson and Delilah.

The Democrats also have two Lincoln-like choices to offer reconciliation to the electorate, John Edwards of North Carolina and Barack Obama of Illinois. Both have the advantages that Lincoln enjoyed: a negligible record in Washington, unknown or minor positions on the great issues, and ambitions that seem as fresh as an ingenue’s. Also, Messrs. Edwards and Obama do not have negatives, especially when compared with the baggage train behind Mrs. Clinton. If there are problems for the twin Lincolnites, it will be that there are junior versions of them also in the chase who can compete with their attraction as newcomers, such as Tom Vilsack of Iowa, who has announced, and Bill Richardson of New Mexico, who is yet unannounced.

Could either party suffer the fate of the Democrats in 1860, when a potent core bolted the convention to nominate a troublemaker? The Republicans risk just such a fatal event. No matter his palaver about creationism or Liberty University or stem cells, Mr. McCain cannot satisfy his party’s right, who treat him as a poisoned well. If there is a GOP disaster in 2008, it will be a rump revolt that holds a virtual convention to nominate a barnburner in the Pat Buchanan mold.

At year’s end, the contest in both parties looks volatile enough to make the major candidates, Mr. McCain and Mrs. Clinton, into very famous almosts like Seward and Douglas. More perilous, the politics of the war in 1860 made potentates of unappealing opportunists such as Jefferson Davis of Alabama in the South and Benjamin Butler of Massachusetts in the North. In 2008, with jihadist threats as frequent as weather reports, it is not farfetched to compose another such opportunity for candidates of no fidelity, faction, or purpose, such as Mayor Bloomberg or Wesley Clark of no particular place, to take command of a fractured, panicky ballot.

Mr. Batchelor is host of “The John Batchelor Show,” now on hiatus.