In the marathon Democratic presidential race, nothing that happens between now and the finish line is likely to make it much easier for the party to choose between Sens. Barack Obama and Hillary Rodham Clinton.
Both of their campaigns agree that even if Michigan and Florida hold do-over primaries, Obama is likely to maintain his lead in pledged delegates, albeit a relatively narrow one. With revotes in Michigan and Florida, Clinton might overcome Obama's advantage in the total popular vote, but even if she passes him, the margin is likely to be infinitesimal.
Nor are the mirror-image electoral coalitions that each candidate has assembled likely to change much. Each candidate, in fact, has attracted such a distinct and durable base of support that the party could probably save time and money by replacing the remaining 10 contests with computer simulations based on each state's demographics.
All of which suggests that Obama and Clinton may spend (at least) the next three months bloodying each other (rather than targeting presumptive Republican nominee John McCain) without much altering the fundamental question confronting their party: If Obama leads among pledged delegates but remains short of the number required for nomination, should the unpledged superdelegates overturn that verdict from the voters and present the nomination to Clinton on the grounds that she would make a stronger general election candidate?
That wouldn't be an easy decision for the superdelegates under any circumstance. It is even tougher because current evidence provides no clear verdict on which candidate would compete more effectively against McCain. Indeed in early general election polling, Obama and Clinton display many of the same strengths and weaknesses against McCain that they have shown against each other.
Obama has usually polled better against McCain than Clinton does, but the difference is typically modest, and in some surveys conducted since Clinton's Ohio and Texas victories the gap has vanished. Probably more revealing at this point is the contrast between the coalitions that Obama and Clinton are attracting.
With the general election choice still so unformed for voters, the trends are not consistent across all surveys. Still, the emerging picture indicates that against McCain, Obama might cast a wider net than Clinton, but also need to plug more leaks in his boat.
In a recent Pew Research Center survey, for instance, Obama carried independents against McCain by 6 percentage points, while McCain carried them against Clinton by the same amount; the difference mostly reflected Obama's stronger showing among independents earning at least $50,000 annually. Other surveys, such as a Quinnipiac University poll in the key battleground of Pennsylvania, have found that Obama also swipes more Republicans from McCain than Clinton does.
This all tracks Obama strengths familiar from the primaries. But primary-season trends more troubling for Obama are also persisting. In the national Pew survey, and in Quinnipiac polls of Ohio and Pennsylvania, Obama lost more Democrats to McCain than Clinton did. In the Pew survey, Obama struggled particularly among the same blue-collar white Democrats resisting him in the primaries: Fully 30 percent of white Democrats earning less than $30,000 a year preferred McCain over Obama. Clinton would lose only half as many of them to McCain, the polls indicate. In the Quinnipiac surveys, Clinton likewise outpolled Obama against McCain among white women without college degrees, a key general election swing group that has overwhelmingly preferred her in the primaries.
Findings like these help explain why many Democrats think Obama offers greater potential rewards as a nominee, but also presents greater risks. If Obama runs well, he seems more likely than Clinton to assemble a big majority and trigger a Democratic sweep -- not only by attracting independents and crossover Republicans but also by increasing turnout among African-Americans and young people.
But if Obama stumbles, he could face a greater danger of fracturing the traditional Democratic coalition by losing seniors and blue-collar whites to McCain, principally on security issues. Clinton's reach across the electorate may not be as long, but her grip on her voters could be firmer.
The larger point is that each of these talented candidates continues to display stubborn electoral vulnerabilities that the other might reduce. That's why talk of their running together is likely to continue no matter how much they bruise each other in the grueling and probably inconclusive weeks ahead.