As this is written, the final numbers are not in, but the results of the Iowa precinct caucuses are clear. Two candidates that almost no one in the country had heard of four years ago — Democratic Senator Barack Obama and Republican Mike Huckabee — have emerged victorious. And by mighty impressive margins, particularly so if you factor in turnout.

The Iowa Democratic Party estimated Democratic turnout at 220,000, nearly double the 124,000 recorded in 2004. The Republican turnout appears to have increased from 87,666 in the last contest in 2000 to something like 114,000. That would be impressive, except that it puts Republican turnout at about half the Democratic level, in a state that was split just about evenly between the two parties in the past two presidential elections.

The Des Moines Register was criticized for its poll last week that projected a substantial boost in caucus-goers by self-identified independents. But that poll seems to have been pretty much spot on. Turnout had a big hand in Mr. Obama’s victory, as he carried young voters by an overwhelming margin and led Senator Hillary Clinton among all voters under 60. He also seemed to lead among well-educated and upscale voters.

Iowa Democrats’ method of scoring the results by “state convention delegate equivalents” understates Mr. Obama’s popular vote margin. He won big in large counties like Polk (Des Moines) and university counties like Johnson (Iowa City), which are underrepresented at Democratic state conventions.

John Edwards, in contrast, gamed the delegate system ably by concentrating on rural counties, which are overrepresented. He ended just ahead of or in a virtual tie with Mrs. Clinton in the official count — though he ran behind in the popular vote. His vote was down sharply in Polk County, which he carried four years ago. Even though Mr. Edwards has been stumping hard in Iowa for six years, he appears to have come in slightly behind his showing in 2004, when he ended up a close second to John Kerry.

Mr. Edwards will probably shoulder on in New Hampshire, but it has an aversion to Southerners, and he finished a poor fourth last time around. With far less money than Mrs. Clinton or Mr. Obama, his candidacy appears headed to an unhappy end.

So the Democratic race is now most likely a two-candidate contest between Mr. Obama, who can bring large numbers of new and young people into the caucus process, and Mrs. Clinton, who has the vestigial loyalty of the party’s historic constituencies but, at least in Iowa, not a whole lot more.

The entrance poll showed Mr. Obama beating her among women, 35% to 30%, and among men, 35% to 23%. Keep in mind that the turnout, though a record high, amounted to only about 10% of registered voters who lean Democratic. Mrs. Clinton can hope to do better among the larger primary electorates in New Hampshire, South Carolina and other contests. But she’s obviously no longer the overwhelming favorite. The contest between them is likely to be resolved by February 5, when more than half the nation will have had a chance to vote.

The outlook for Republicans is less clear. Mr. Huckabee showed he had the capacity to bring new voters to the polls: In this year’s entrance poll, 60% of Republican caucus-goers classified themselves as “born-again Christians,” as opposed to the 38% “religious right” in the 2000 caucuses. But among the 40% non-born-agains, Mr. Huckabee won only 14% of the vote. There are many Christian conservatives voters in some upcoming Republican contests — though not in New Hampshire. But Mr. Huckabee has to expand his appeal to be a real contender.

The onlooker who is the big winner is third-place John McCain. He’s been leading or tied with Mitt Romney in recent New Hampshire polls, after Mr. Romney was leading there for months. And while Mr. Romney has the capacity to self-finance to February 5 and beyond, it’s not clear he’ll be a real contender if he fails to win in New Hampshire.

Fred Thompson had a disappointing finish in Iowa. Rudy Giuliani didn’t play there, but whether he can recover his high standing in polls in Florida and the big February 5 states is not so sure.

All this threatens to set up arduous contests in both parties with, until recently, unknown candidates able to expand their party’s constituencies facing well-known warhorses who may find it tricky to win without antagonizing those constituencies. A tough spot for both parties all around.