Heading into Tuesday's unprecedented day of voting in two dozen states, a degree of order is finally emerging in the dramatic races for the presidential nominations of both parties.
Public opinion and leadership support are finding their way to the same destinations, pointing to a clear favorite and a single viable alternative in each race.
John McCain has the easiest path remaining to the Republican nomination, with Mitt Romney needing some kind of dramatic breakthrough Tuesday to keep his hopes of an upset alive.
On the Democratic side, the battle is more even, but the advantage has shifted back to Barack Obama - thanks to a growing but largely unremarked tendency among Democratic leaders to reject Hillary Clinton and her husband, the former president.
The New York senator could still emerge from the "Tsunami Tuesday" voting with the overall lead in delegates, but she is unlikely to be able to come close to clinching the nomination. And the longer the race goes on, the better the chances that Obama will ultimately prevail, as more elected Democratic officials and candidates come to view him as the better bet to defeat McCain in November.
As the race has moved from contests in small states such as Iowa and New Hampshire to the national dimension of Tuesday's voting, the role of the endorsements and leadership testimonials has increased. The candidates simply lack the time and resources to make personal appeals to very many voters.
Had McCain not invested that personal time in New Hampshire, with more than 100 town meetings where he argued for the correctness of his views on the Iraq War, he could not have reversed the summertime disaster that overtook his campaign, when he ran out of money and lost most of his senior staff.
But after turning back Romney in New Hampshire, the Arizona senator picked up significant establishment backing in South Carolina and Florida - the hardcore Republican states where he had to show his credentials. He campaigned in South Carolina flanked by Tom Coburn and Jack Kemp, icons of social and fiscal conservatism, and won Florida thanks to last-minute endorsements from Gov. Charlie Crist and Sen. Mel Martinez.
Now, with defeated Rudy Giuliani adding his voice to the chorus of endorsements, and with Mike Huckabee remaining in the race to challenge Romney from the religious right, McCain appears poised to lock up the nomination.
Unelected conservative ideologues - Rush Limbaugh and George Will - can mutter in frustration, but Republican politicians recognize what was written here as long ago as last Dec. 2: "If the Republican Party really wanted to hold on to the White House in 2009 ... it would grit its teeth, swallow its doubts and nominate a ticket of John McCain for president and Mike Huckabee for vice president - and president-in-waiting."
The Democratic race remains harder to handicap, in part because Clinton already has demonstrated her resilience by fighting uphill battles to prevail in New Hampshire and Nevada and because she retains formidable alliances and organizational strengths.
But the past two weeks have seen a remarkable shift of establishment opinion against her and against the prospect of placing the party's 2008 chances in the hands of her husband, Bill Clinton.
The prominence of his role in New Hampshire and South Carolina, and the mean-spiritedness of his attacks on Obama, stunned many Democrats. Clinton's behavior underlined the warning raised in this column before Iowa, by a prominent veteran of the Clinton administration, that the prospect of two presidents both named Clinton sharing a single White House would be a huge problem for the Democrats in November if she is the nominee.
The negatives on the Clintons have brought much support to Obama, most notably that of Ted Kennedy, the most prestigious figure in the Democratic establishment in Washington. But it is also Obama's own appeal that is being talked about across the country from Massachusetts to Arizona by the younger generation of governors, senators and representatives who share with him an eagerness to "turn the page" on the battles of the past.
Obama is not inevitable, but the longer the race continues, the greater that hunger. And the growing recognition of McCain's appeal to independents also works in Obama's favor.
E-mail nationally syndicated columnist David Broder at email@example.com.