The generic ballot edge that Democrats had maintained for the better part of the last two election cycles disappeared; in the latest NBC-Wall Street Journal poll, 43 percent of respondents said they preferred a Democratic-controlled Congress while 40 percent said they would like to see Republicans running things on Capitol Hill. (As recently as April, Democrats had a nine-point lead on that question.)

Recruitment also began to pick up for Republicans, with top-tier candidates who might have taken a pass in years past stepping up to run — for example, state Sen. Bob Gibbs in Ohio’s 18th District and former U.S. attorney Tim Griffin in Arkansas’s 2nd.

Those developments led some of the nation’s leading political prognosticators, such as Charlie Cook and Larry Sabato, to predict that Democrats were headed for a world of hurt in 2010, with the loss of 20 or more House seats not out of the question. (A third respected political analyst — Stu Rothenberg — was slightly more circumspect about just how bad the environment is for House Democrats.)