Even so, the population shifts open up a number of opportunities to add some new "safe" seats to the GOP's forces, and a number of Republican strategists are already testing boundary-line changes -- precinct by precinct, street by street -- on computer models that take full advantage of the new census data.
"The Republicans are going to have their hand on the computer mouse, and when you have your hand on the computer mouse, you can change a district from a D to an R," Kimball W. Brace, president of Election Data Services, told the New York Times.
But the net House gains the Republicans hope to achieve under redistricting and reapportionment may pale to the gains they may make in the Senate in 2012.
The reason: 23 Democratic senators -- many of whom are on the endangered list -- will be up for re-election, compared to a mere 10 Republicans, most of whom are considered safe. Among them:
-- Claire McCaskill of Missouri: A down-the-line vote for the entire Obama agenda, she won her seat in a 49.6 percent squeaker in 2006. This month, a Democratic Public Policy Polling survey showed her approval rating at a dismal 43 percent. Former Sen Jim Talent is considering a rematch.
-- Sherrod Brown of Ohio: After last month's Democratic blood bath, with the GOP winning the Senate and governorship races and a handful of House seats, Brown is in trouble. He's a knee-jerk liberal vote for Obama's agenda, and the PPP poll shows just 45 percent would vote to re-elect him now.
-- Jim Webb of Virginia: Republicans are back in charge of this conservative state, and Webb, who won his seat in an upset in 2006 by a margin of 0.6 percent, will have to defend a pile of big-spending liberal votes, beginning with Obamacare. Former Sen. George Allen is weighing a rematch.
-- Jon Tester of Montana: Tester won his first term by just 3,500 votes with strong liberal netroots support, but the left has turned against him bitterly. Jean Lemire Dahlman, the state's Democratic national committee chair, says, "He's alienated his base in the progressive Democratic circles." GOP leaders see this seat as "a strong pickup."
The Democrats enter the 2012 presidential election cycle with the certain prospect of losing a clutch of House seats, even before any ballots have been cast, and nearly half-a-dozen freshmen senators are on the endangered candidate's list.
But that's only half of their troubles. This time they will be on the same ballot with Barack Obama.