There has been various circumstantial evidence that the public’s dissatisfaction with the performance of Congress, particularly during the debt ceiling debate, could threaten the Republican majority in the House of Representatives. Disapproval ratings for the Congress are at record highs, as are disapproval ratings for the Republican Party. Other polls show record numbers of Americans saying that their representative should not be re-elected, that most members of Congress should not be re-elected, or both.
What we haven’t had, however, are polls comparing Democrats against Republicans in a direct way. That’s why the poll that Gallup published Friday ought to concern Republicans. It shows a 7-point Democratic advantage on the generic Congressional ballot — meaning simply that more Americans told Gallup they plan to vote for a Democrat for Congress next year. Although the generic ballot is a crude measure, it is probably the best macro-level indicator of the direction that the House is headed in.
Last year, Republicans won the popular vote for the U.S. House — essentially what the generic ballot is trying to measure — by 7 percentage points. So a poll showing Democrats 7 points ahead instead is a pretty significant swing.