The population continues to shift from Democratic-leaning Rust Belt states to Republican-leaning Sun Belt states, a trend the Census Bureau will detail in its once-a-decade report to the president. Political clout shifts, too, because the U.S. must reapportion the 435 House districts to make them roughly equal in population, based on the latest census figures.
The biggest gainer will be Texas, a Republican-dominated state expected to gain up to four new House seats, for a total of 36. The chief losers - New York and Ohio, each projected by nongovernment analysts to lose two seats - were carried by Obama in 2008 and are typical of states in the Northeast and Midwest that are declining in political influence.
Democrats' problems don't end there.
November's elections put Republicans in control of dozens of state legislatures and governorships, just as states prepare to redraw their congressional and legislative district maps. It's often a brutally partisan process, and Republicans' control in those states will enable them to create new districts to their liking.
The combination of population shifts and the recent election results could make Obama's re-election campaign more difficult. Each House seat represents an electoral vote in the presidential election process, giving more weight to states Obama probably will lose in 2012. The states he carried in 2008 are projected to lose, on balance, six electoral votes to states that his GOP challenger, Sen. John McCain of Arizona, won. That sets a higher bar for Obama before his re-election campaign even starts.
"The way the maps have shifted have made Obama's route to success much more difficult," said Republican Party spokesman Doug Heye. He said the Republican takeover of several state governments on the eve of redistricting efforts was "a dramatic shift."
Republicans now control the governor's offices and both legislative chambers in competitive presidential states such as Ohio, Pennsylvania, Florida, Indiana, Maine and Wisconsin. They hold the governors' chairs in other crucial states, including Nevada, New Mexico, Virginia and Iowa.
When Obama carried those states in 2008, most had Democratic governors happy to lend their political operations to his cause. Now he will run where governors can bend their powers against his administration's policies and his campaign's strategies.
Democratic Party spokesman Brad Woodhouse said his colleagues are aware of the challenges they face, "but we are putting a plan in place to maximize our opportunities, minimize potential setbacks and ensure that the process in each state is fair and done in accordance with the law."
The Democrats' few bright spots include California and Illinois, where they control the legislatures and won hard-fought races for governor last month.
Of course, any number of things can happen before the 2012 elections, and Obama and other Democrats may come roaring back. Republicans might help them by pushing their luck and trying to draw more Republican-leaning House districts than the elections of 2012, 2014 and beyond will support.
State politicians use detailed, computer-generated data on voting patterns to carve neighborhoods in or out of newly drawn districts, tilting them more to the left or right. Sometimes they play it safe, quietly agreeing to protect Republican and Democratic incumbents alike. But sometimes the party in control will gamble and aggressively try to reconfigure the map to dump as many opponents as possible.
"The danger you run is trying to be too clever and cutting those margins too thin," said Tim Storey, a redistricting authority for the nonpartisan National Conference of State Legislatures.
That's what Pennsylvania Republicans did 10 years ago, when they controlled the redistricting process after the 2000 census. Determined to turn the Democrats' 11-10 House delegation advantage into a 13-6 Republican edge (after the state lost two seats due to sluggish population growth), Republicans created new districts that forced several Democratic incumbents to run against each other. Democratic lawsuits in state and federal courts failed to overturn the "grotesque district boundaries," as the Almanac of American Politics called them.
Republicans initially won 12 of the state's newly drawn House districts. But when Pennsylvania voters shifted more toward Democrats in the next few years, thinly protected Republican lawmakers lost their seats. By 2009, Democrats had a 12-7 advantage.
Pennsylvania's partisan warfare was mild compared with the Texas redistricting imbroglio of 2003. Republicans, who had just taken over the state government, refused to live eight more years with a political map that had given 17 U.S. House seats to Democrats, and 15 to the Republicans.
Prodded by then-House Majority Leader Tom DeLay, Texas Republicans took the rare step of drawing a second statewide political map only three years after the census - with boundaries certain to send more Republicans to Washington.
More than 50 angry Texas House Democrats fled to a Holiday Inn in neighboring Oklahoma to keep the Legislature from having the quorum needed to pass the Republicans' plan. The "Killer Ds" eventually returned to Texas' capital in Austin, and Republicans adopted their new congressional district map. It helped them win 21 House contests, compared with the Democrats' 11, in the next election.
The Texas plan survived a legal challenge filed under the U.S. Voting Rights Act, a law meant to protect the rights of ethnic minorities. Although critics say the law has outlived its purpose, it still covers virtually all of nine states, mostly in the South, and portions of another half dozen states.
The Voting Rights Act, plus a hodgepodge of court rulings on issues such as one-person, one-vote guidelines, complicate the task of state officials who draw district lines.
"There are so many competing criteria that it's a massive balancing act," Storey said. Partisan goals certainly play a role, he said, but it's not only about that.