McClatchy’s David Lightman, for one:

Hillary Clinton apparently thought that she had a killer sound bite during Thursday’s debate when she ripped Barack Obama as a promoter of “change your can Xerox.”

Instead, the audience booed, critics winced and once again the New York senator’s attempt to demonize her rival fell flat, another illustration of how 2008, at least so far, is the year that negative campaigning just doesn’t work as it once did.

Many reasons are offered, some conflicting: burnout, Clinton seeming polarizing against Obama’s positivity, voters being excited about both Clinton and Obama, information overload, higher tolerance for misbehavior, and so on.

The question of why negative campaigning does not work in a general sense is silly, inasmuch as the evidence on the effectiveness of negative campaigning is inconclusive.  Moreover, I would argue the evidence is inconclusive because negative campaigning, like any other type of campaigning, depends on an array of variables that are near-impossible to account for in any general study.

For example, on a micro-level, it could be argued that the reason Clinton’s debate zinger fell flat was that the debate was held on a college campus in Austin, which likely skewed the audience pro-Obama.

At a broader level, there is something to the contrast in the candidates’ images.  Democrats undertand that Clinton would be a polarizing general election candidate, so watching her zing this year’s Man of Hope plays into a perceived weakness.

It is a perceived weakness because the public mood this year favors change in the form of bipartisan cooperation.  In a different year, primary voters might have preferred a feisty verbal pugilist — or at least appreciated the value of negativity in a general election.

However, negative campaigning is always more risky in a primary, inasmuch as the audience is likely to be somewhat favorably disposed to the target.  Mitt Romney’s attacks did not work because McCain and Huckabee were perceived as likeable by chunks of the GOP electorate.  Moreover, Romney had not sufficiently built up his positive rationale before going negative.  Similarly, Hillary Clinton’s image as The Glacier make it more difficult to go negative, particularly against the seemingly likeable Obama.

Furthermore, primary voters are likely to fret that too much friendly fire in a primary weakens the nominee in a general election.  This may be true occasionally, though this is again context-specific.  In 1988, someone would have used Willie Horton to attack Mike Dukakis in the general election, even if Al Gore had not used him in the primaries. 

In contrast, in this cycle, most of the issue differences between Clinton and Obama are marginal, with the notable exception of Iraq.  Clinton cannot find traction on issue differences, so her attacks tend more toward the personal, which is always riskier.  Conversely, Obama can criticize Clinton’s vote to authorize military force without suffering himself among Democrat primary voters.  Indeed, the McClatchy piece noted Mitt Romney’s attacks on McCain’s record to show that negative campaigning is ineffective, but completely missed how Obama has effectively used the Iraq issue to question Clinton’s judgment, and by extension, her claim to experience. 

If Obama is the nominee, he can attack McCain’s similar vote and have the general unpopularity of the mission behind him.  On the other hand, McCain will be a more robust defender of the mission and current progress in Iraq, as well as more willing to debate the consequences of a quick withdrawal than Clinton could be in Democratic primaries.  Obama will attack McCain as a warmonger; McCain will attack Obama as a dovish naif not to be trusted to be commander-in-chief.

In neither the primaries nor the general will voters be turned off generally by negative campaigning on an issue like Iraq, because voters ultimately recognize that elections are about making choices on issues as well as personal characteristics. 

Of course, it may be possible to overplay an otherwise legitimate attack — Obama’s claim that McCain wants to be “mired in Iraq for a hundred years” is a distortion that may play well in a primary, but not in the general.   The audience is broader and less partisan.  And McCain is viewed more favorably by voters than Clinton.

As a nominee, Obama would do much better against McCain with the attacks he has dressed up as compliments.  When Obama thanks McCain for his many years of service — as he does on the stump — he is not only painting McCain as the candidate of the past, but also subtly recalling the standard speech someone gives when retiring an old man to pasture.  McCain will have difficulty responding to such attacks, as pointing out the underlying attack only reinforces it.