Surveys and news reports show there are now nearly 100 "battleground" House districts where the races are likely to be tight on Election Day (Nov. 2). That's up from about 70 battlegrounds in June. The vast majority of those seats are now held by Democrats. To get a feel for what the districts' voters are thinking, NPR engaged Democratic firm Greenberg Quinlan Rosner Research and Republican firm Public Opinion Strategies (complete results here). They surveyed 1,200 "likely voters" for the latest NPR Congressional Battleground Poll. A similar survey done for NPR in June signaled problems ahead for Democrats. This latest poll does as well, though the advantage for Republicans has narrowed slightly. Note: The survey was done of "land-line" users only. Calls were not made to cell phone users. Public Opinion Strategies' Glen Bolger says that could mean some younger, possibly Democratic-leaning voters were missed.