Recently, three respected national surveys—Gallup, Pew, and now Battleground—have given Republicans a double-digit edge among likely voters. While I’m no expert on this history of public opinion research, I can think of no parallel to these findings during my three decades of involvement in national politics.

There are only two possibilities: Either this election is so distinctive that existing likely voter models, which are derived inductively from past experience, are simply inapplicable, or we are looking at a potential Republican sweep of historic proportions, larger even than 1994, long regarded as the ne plus ultra of contemporary swings. If so, the oft-repeated characterization of this election as a “wave” seems inadequate; tsunami would be more like it.

In particular, these findings have implications closely contested Senate races, which are numerous right now. During recent decades, three elections—1980, 1986, and 2006—have featured tossup races that all ended up falling in the same direction. If Republicans enjoy anything like a double-digit edge on November 2, 2010, may well be another such election.

This is a time of testing—for Democrats, but also for the profession of survey research. On November 3, one or the other will have to go back to the drawing board.