As previous posts have suggested, the fundamentals point to a continued GOP majority in the House. To have a chance at regaining the chamber, the Democrats would have to be running flawless races. At The Atlantic, Molly Ball explains that they aren't.
Take California's 21st district, a slightly Republican-leaning Central Valley seat newly created by redistricting. Democrats' first-choice recruit got cold feet; their second choice, a city councilman with the felicitous name Blong Xiong, didn't make it through the primary; and now they're stuck with their third, who does not live in the district and has never held office. Democrats could still win the seat, but it's far less likely. And any House hope for the party requires a major sweep in California.
A few more examples:
* In Illinois' 13th district, the candidate recruited by national Democrats didn't make it through the primary, and the winner in his stead is a perennial candidate who's lost his last three tries for Congress. (Illinois is another big, strongly Democratic state where the party must maximize its success in order to rack up big national gains.)
* In Connecticut, the speaker of the state House, Chris Donovan, is still favored to win the 5th District Democratic primary despite a federal investigation into illegal campaign contributions. ("We really don't know where the stuff came from," his campaign manager said a couple of weeks ago.)
* Democrats are even in danger of losing a House seat in Rhode Island -- Rhode Island! -- thanks to revelations about Rep. David Cicilline's mismanagement of Providence when he served as its mayor. Obama won the district by a more than 2-to-1 margin in 2008. (Josh Kraushaar points to two moresolidly Democratic seats that could go to the GOP because of Democratic candidates' vulnerabilities.)
* In Arkansas, Democrats' preferred candidate in the 4th District lost the primary to a state legislator who blamed opposition to health-care reform on racists who "don't want to pay for no more n----- babies."