So many rats, such a large iceberg, so little time:

Primary filing deadlines will have passed in about half of all congressional districts by late April, and it will then be clear whether Republicans face a wave of retirements, said Amy Walter, House editor of the Cook Political Report. Nineteen House Republicans retired in 2004.

Democrats now hold 201 House seats and need 218 to regain majority control. Boehlert’s and 10 of the other seats that Republican incumbents are abandoning are rated as “competitive,” according to the Cook Report.

Expecting a favorable political environment in part due to the president’s falling popularity, Democrats believe they can retain almost all of their present seats and knock off at least five to 10 Republican incumbents in closely divided districts or where scandal allegations are a factor. Still, to take control, Democrats may have to win as many as a dozen of the seats held by retiring Republicans.