The "Clinton coalition" referred to here is Bill Clinton's coalition of voters, not Hillary's (although I'm sure there's a lot of overlap). The article gives a detailed analysis of the recent election in Virginia, which I did not quote here, but it definitely worth a look.
The historical base of the Democratic Party for two centuries has long been what Jay Cost and I call Jacksonians: Culturally conservative, hawkish, and populist whites located throughout the South and Border states. They began breaking away from Democrats in the 1950s and 1960s – their reaction to the Party's embrace of unions, blacks and liberals is a story is so well known there's no need to rehash it here.
But this group remained at least in play for the Democrats. Clinton inherited a coalition consisting of minorities, liberals, urban voters, and a decent remnant of Jacksonian voters in the Ohio River Valley and the South, who still preferred a moderate-to-conservative Democrat to a Republican. This coalition became a majority coalition when Clinton used a combination of fiscal conservatism and social moderation to bring suburban voters on board. This was a huge innovation for Democrats; suburbs like Nassau County, NY, Orange County, CA and Fairfax County, VA had fueled the rise of the Republican parties in those states. Clinton moved them substantially toward his side. This coalition allowed him to win by eight points in 1996; absent Perot and a last-minute fundraising scandal, he probably would have won by more.
Clinton intuited that suburban voters are, generally speaking, culturally cosmopolitan – they don't like it when you call someone "macaca," and aren't crazy about the religious right. But they're generally not particularly socially liberal either, and are fans of "law and order." They like taxes low and appreciate economic growth, but like good schools and a clean environment. Having to balance a bunch of spending priorities with somewhat limited income in their daily lives, balanced budgets are the ultimate "good government" indicator for these voters.
Clinton delivered on all of these issues, keeping tax increases fairly small, and balancing the budget for much of his term. In so doing – and this is very important – he re-branded the Democrats as the party of fiscal responsibility, economic growth, moderate taxes, and smart government. In other words, he finally shed the "Carter" label for the Democrats. This, in turn, made it plausible for his much more liberal heirs to benefit from this presumption of competence for Democrats – one that they probably would not have enjoyed without him.
Obama was able to win even without this branch of the Democratic party because he generated such intensity among the remaining portions of his base. In other words, while his base wasn't as broad as Clinton's, it was deeper. Faced with vanishing 401ks and home values, and disgust with Bush's presidency, suburbanites flocked to him. Liberals were enthralled to finally elect one of their own. And minorities turned out heavily for the opportunity to elect the first black President.
But this presents a problem. You only get to elect the first black President once, and governing a coalition of suburbanites, poor blacks, and upper class liberals isn't easy. It is hard to keep that enthusiasm up. And with the Jacksonian wing of the party gone, if that enthusiasm dissipates, or if one of the coalition groups becomes disgruntled and starts to shuffle out the door, the party isn't left with much.
States with a Democratic base of liberals, urbanites, and minority voters -- like California and New York -- haven't moved much against Democrats. Obama's polling numbers, as well as those of Democratic candidates for Governor and Senator, in classic "Emerging Democratic Majority" states like Colorado and Nevada are not looking good at all. And of course in Jacksonian states like Kentucky, he's below 40%.
This doesn't mean that Democrats are doomed in 2010. An improved economy, Republican missteps, and a host of other factors could keep the band together for them. Maybe some of the more marginal voters that Obama brought to the polls to enact hope and change will return in 2010 to keep hope alive. But the personal nature of Obama's victory is starting to show its downside for downticket Democrats.
The Clinton coalition is looking creaky. If Obama doesn't improve and the coalition comes apart, Democrats could find themselves weaker than they were even in the 1980s and 1990s.
If this happens, and I'm sorry to say it but the Clintons will have no one but themselves to blame. They are so loyal to their "party" and have backed Obama even when it was obvious they shouldn't. It could cost them in the end.
I do not think the author blames the Clintons, rather that Obama and his policies are weakening the DNP brandname that Clintons had restored after Carter.