I left out Boswell in my comments above. This is not one of Boswell's past opponents. Former St. Sen. GOP Pres. Jeff Lamberti is easily the strongest challenger Boswell has had. He's well-funded and moreover Boswell was MIA for several months due to health concerns. However, with Boswell evidently in full recovery and back to his Congress work and the campaign trail, this one may very well be trending down. This is also a total toss-up district: 49.69% Bush to 49.60% Kerry in 2004.
You're right to point out Leonard Boswell. There is another issue, albeit one that no one feels comfortable discussing. Boswell is aging and has had severe health problems recently. A few months back, he had a very serious operation. So there may be voters questioning his ability to carry on his job responsibilities.