Moreover, the Republican Party has a different image than it did in 1994. At that time, Republicans had been out of control of Congress for long enough that they were able to present themselves as the party of change. They were viewed unfavorably by just 39 percent of Americans. By contrast, 57 percent said in February that they had an unfavorable view of Republicans in a New York Times/CBS News poll.
While it's true that Republicans are viewed more negatively than they were in 1994, that's not the relevant comparison in 2010. Electoral politics is a zero-sum game. What matters is the strength of the Republican image relative to Democrats. And as I showed a couple of weeks ago, the gap between the parties' images is now comparable to 1994:
As such, there's no reason to think that the GOP's negative image will protect Democrats, especially given the likelihood that the Republican brand will continue to gain luster (as it did between June and November 1994).
For a better analysis of the state of play for November, see Mark Blumenthal's National Journal column on the generic ballot and Charles Franklin's accompanying blog post on Pollster.com (where I cross-post). Franklin's key graph comparing generic ballot trends over time looks very ominous for Democrats: