How you interpret that cryptic remark depends on what you (or Nader) mean by "landsliding." We can all agree that Nader means "beat Republicans by landslides," but for Nader himself that also means doing what is necessary to ensure a landslide. If Democrats haven't been able to reclaim the House of Representatives from Republicans with landslide victories, Nader assumes that there's something Democrats can and should do that's not getting done.
In other words, the Democrats are so beholden to their own big-money contributors that they can’t fight on issues that they know have overwhelming public support. Plainly, the House Democrats raised enough money. They benefited from their gerrymandering, too. On the issues, the Democrats had a huge advantage. Yet instead of confronting Republicans in district after district with the vicious Ryan budget and the Boehner Band’s voting record, the Democrats displayed open defeatism.
In Nader's account, Democrats won't run a real rabble-rousing social-justice campaign -- the kind that Nader thinks would assure them landslide victories -- from fear that corporate donations would dry up during that very campaign. This is not an implausible interpretation, but as I said, another reading is possible. What if Democrats are less concerned about the consequences for a particular campaign or candidate of the kind of aggressive campaign Nader wants than they are about the long-term financial consequences of actually landsliding Republicans? While Nader presumes that Democrats maximize campaign donations by playing it safe on economic issues and not offending corporate donors, what if the Democrats themselves believe that they maximize donations by stressing the perpetual imminence of the Republican menace in a way that'd no longer be possible were the GOP landslided into irrelevance? Nader's notion may be consistent with a critical analysis of Democrats' ideological limitations, my alternative interpretation may better reflect the reality of recent campaigns. Does anyone believe that Democrats didn't campaign by demonizing Republican celebrities and hyping their threat to the well-being of middle and working class Americans? I think we know better. If anything, Democrats would probably prefer to campaign entirely on the level of personality, using the Republicans and their more obnoxious allies like Rush Limbaugh to scare people into voting Democratic, rather than pitch policy promises they don't expect to fulfill. Rather than talk about Ryan's budget, or Boehner's voting record, they simply want to talk about Ryan and Boehner and make them look and sound as mean as possible -- not exactly a major challenge, to be fair. Muting their own commitment to social justice may help maximize donations to Democrats, but what really keeps the money flowing, probably from across the wealth spectrum, is the viability of the Republican threat. If Democrats are more concerned about maximizing donations than governing the country, then naturally they wouldn't want to eliminate Republicans from power as completely or permanently as many Democratic voters might like. A reader who calls himself "Silly Rabbit" expresses this viewpoint more sharply on the comments thread for the Nader article.
The Democrats--and especially Obama--WANT a strong Republican Party. Why? Because a strong, vocal, organized, intransigent and committed Republican Party gives the Democrats cover and an excuse for not accomplishing the ideals they publicly posture as wanting to accomplish, but in truth don't want to accomplish at all. In short, without strong Republicans, the Democrats would have to do the things they present themselves as wanting to do, but in reality (for fear of offending the monied interests they are also a part of and/or aligned with) really have no intention of accomplishing.
None of this greatly contradicts what Nader assumes. We seem to agree that Democrats aren't very interested in an intensely progressive and/or populist campaign or program. We differ in that Nader seems to blame this on cowardice while I suspect cynicism at the root. Before the Sean Wilentzes of the world jump on me, I'll happily concede that many Democrats see themselves sincerely as compassionate stewards of the public good. I don't doubt that many if not most Democrats want to help people with a fervor alien to Republicans. The problem with Democrats, and the difference between the Democratic party and democratic rule, is that the party always wants to help on its terms, while telling the rest of us that those are the best terms we can get. Those who accept those terms and tell us the rest of us to accept them unconditionally are the real defeatists.