Democrat congressional possibilities

US Congressional elections are so difficult to predict. With a weaker party system (although one that is becoming more polarised) much depends on local candidates and whether sitting MPs are standing. An interesting article here uses a basic statistical model to predict this year's outcome and suggests that the Democrats have a chance of winning the 15 seats needed for a House of Representatives majority:
The current model predicts a net Democratic gain of 10 seats. When we factor in a four-seat margin of error, the model projects that as of today, under current conditions, and without speculating about what the national political environment may do between now and November, Democrats will make a net gain of six to 14 seats. With a bit of luck -- or a wave of any size -- Democrats might even grasp their gold ring: 15 seats.
This is encouraging, but remember that a good Democrat performance in 2006 might be followed by a slight regression in 2008 (even if the Democrats win the Presidency), and a narrow Democrat majority will hardly offer much hope of progressive legislation. This could change if the Republicans crash and burn, but although the economic recovery looks unexpectedly sluggish (with quarterly GDP growth down to its slowest rate in 3 years at 1.1%) I doubt this will occur.