It's hard to argue with history.

Yesterday I wrote a post that highlighted how the current generic congressional poll numbers indicate the possibility of a 50+ gain in the U.S. House for the GOP. It was based upon the analysis of a renowned Democrat statistician.

Now we have another well-respected Democrat consultant that provides us more data that takes yesterday's theme a bit further. His article in the National Journal indicates that history shows a high likelihood the GOP lead in the generic congressional poll will increase.

It is important to remember that the various statistical models are typically based on no more than 16 cases -- the number of midterm elections held since pollsters started asking the generic ballot question. My Pollster.com colleague, University of Wisconsin political scientist Charles Franklin, created charts for each election that can help us reach our own conclusions. These show Democrats losing ground on the generic vote in the last 200 days of 6 of 7 midterm elections held with a Democrat in the White House. But notice that the one exception to the pattern was the most recent: 1998.

Some potential exists for movement in the generic ballot result in the coming months: "Over the last two decades," Franklin writes via e-mail, "we've seen movement of as much as 8 points over the last 200 days, but most years show as little as 2 or 3 points over time."

Either way, Democrats are facing a tough year. "If the Republicans gain another 2 or 3 points, that should give them a significant advantage," Franklin writes, "while if the Democrats recoup ONLY 2 or 3 points, they are still looking at significant losses, at least based on the history of the generic ballot and midterm seat change."

It's hard to spin it any other way than this:

Two of the most well-respected Democratic poll analysts in the nation believe Democrats will lose a very high number of seats in 2010.