There's been so much going on during the last week on the presidential election front that it's obscured some good news on the congressional front.

The latest Democracy Corps "battleground survey" of congressional districts focuses strictly on 45 Republican-held House seats. It showed that Democrats continue to have, and have actually expanded, their advantage in these districts where "Bush won by 12 points in 2004 and Republican members won by the same margin in 2006." This leads the DCorps team to suggest that 2008 could represent rare back-to-back "wave elections" wherein Democrats significantly expand the House majority they won in 2006.

Meanwhile, the nonpartisan and very cautious Cook Political Report, which has been predicting Democratic House gains of 10-20 seats for a while, has just changed its authoritative House ratings to move ten Republican-held districts into more vulnerable categories.

Paul Rosenberg at OpenLeft has a very detailed summary of all the recent polling evidence on the congressional races, but the trends are pretty clear.

It's looking good, and any lingering idea that down-ballot Democrats have to distance themselves from the national ticket to survive should be forgotten. This is a year when being a loud, proud Democrat is definitely a positive.