At this point in the election cycle, spending by well-informed party committees and outside groups has outlined the fronts in the fight for control of the House of Representatives. The Democratic Congressional Campaign Committee and the National Republican Congressional Committee have aired general-election advertisements in 52 House districts, drawing the basic battle lines.

Months of polling, fundraising, candidate recruiting, and analysis of past election results under newly drawn district boundaries have also set the stage for potential gains and losses by either side.

So too have demographics, which provide a neat framework for viewing the 2012 congressional elections. The Republican wave of 2010 was a national victory, but it was rooted in predominantly white districts that were allergic to President Obama and the Democratic agenda. This year, the GOP is mining that terrain for further gains, while Democrats are focusing on the most-diverse Republican-held seats as they try to claw back their majority. Just as the House caucuses have sorted themselves ideologically, they are also sorting demographically.

The GOP netted 63 House seats in 2010, winning a majority nearly as big as the one Democrats had just built. But Republicans almost won the House in a narrow demographic slice of the country. More than half of those gains — 36, almost enough to gain the majority — came in districts where the voting-age population was more than 80 percent white, well above the national average of two-thirds. After redistricting, Republicans control 110 of 142 such districts in the nation.

And even though the GOP conference is larger than it has been in over a half-century, the NRCC is looking back to those very white districts for expansion potential this year. They don't have the incubating national environment of 2010 to work with anymore, but things haven't changed as much in the 80-plus districts. Obama's campaign is fighting to get to victory with 40 percent of the white vote, a small 2-point improvement on House Democrats' 2010 numbers that won't provide much of a baseline for Democratic House candidates in very white districts.

Incumbents such as Reps. Ben Chandler, D-Ky., and Bill Owens, D-N.Y., won tight races in 2010, and national Democrats believe that if the GOP couldn't knock them and others off in the last cycle, they won't be able to manage it this time. But the same challengers are targeting them again, with help from an NRCC that is also targeting all three Democratic members from Iowa, for example. Overall, the NRCC has aired TV ads in 10 districts whose voting-age populations were at least 80 percent white, while another two are considered pretty rock-solid Republican pickup opportunities. The DCCC also felt compelled to air defensive spots in an additional district in this category. All told, House Republicans are playing credible offense in 13 of 32 heavily white districts that Democrats still control.

Meanwhile, Democrats are also reprising some of their few success stories from 2010, but at the opposite end of the spectrum. Republicans netted only 11 seats with voting-age populations more diverse than the national average in 2010, even though Democrats held 125 such seats before the election. The wave broke on that demographic average. Now, Democrats' offensive strategy is disproportionately focused on those heavily nonwhite districts. The DCCC has advertised in 13 of the 51 most diverse Republican-held districts this cycle, and another two are seen as solid enough pickup opportunities that no TV ads were bought.

The most heavily nonwhite districts have also provided the most late-breaking prospects for Democrats. Though the DCCC highlighted the Hispanic challengers to GOP Reps. Jeff Denham and Mary Bono Mack of California throughout the year, their campaigns were seen as second-tier opportunities for Democrats. But former astronaut Jose Hernandez and physician Raul Ruiz successfully mobilized Hispanic support in the districts, both of which have a voting-age population that is over 48 percent nonwhite. GOP outside groups are now racing to help Denham in his campaign's final weeks, and the NRCC just bought $600,000 of TV airtime to come to Bono Mack's defense this week. From Sacramento down to San Diego, California's diverse districts have provided a real bright spot for House Democratic hopefuls there.

Democrats are also targeting more-heavily white districts; the breadth of the GOP's majority demands that the minority play offense everywhere it can. Democratic polling has shown movement in former Rep. Charlie Wilson's direction in southeastern Ohio's 6th District and promise for former state legislator Gary McDowell in Michigan's 1st District, two of the whitest districts in the country, for example. The DCCC and other Democratic-aligned outside groups are directing money there, as well as toward both New Hampshire districts.

But zooming out tells a similar story. Of those 110 heavily white districts that Republicans now control, Democrats are making strong attempts to take back just 14 of them, according to National Journal Daily's analysis. The more demographics change the nation as a whole, the more things are staying the same for both parties in the House.

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