What are the odds of Democrats gaining a majority in the House?

The Wall Street Journal reports:

For all the Republican wins in 2010, Mr. Boehner presides over a modest 25-seat majority. Redistricting has not turned out to be the giant boon some Republicans thought it might be, and the party is playing to beat about 20 sitting Democrats and to win about a half-dozen open seats. But here's the number that counts: An estimated 55 Republican seats are competitive—i.e., at risk—this year.

That includes many of the 89 freshmen who washed into the House in 2010. Those new members bring high enthusiasm, but over the past 30 years parties have lost on average 10% of their rookies in their first re-election effort. If Mr. Boehner bats the average, he's nine down at the start.