It could be six years before liberals can accomplish anything.

We’ve all heard that Democrats are in for a very difficult two years. The new GOP majority in the House of Representatives will wage a campaign to disable health reform, financial regulation, and the EPA; stonewall executive and judicial appointments; slash nondefense discretionary spending (thus undermining the economic recovery); gut Social Security and Medicare; and launch investigations into every possible White House indiscretion—potentially leading to a vote for impeachment. Democrats’ only recourse will be to practice what Howard Dean famously derided as “damage control”—to abandon hope for big progressive accomplishments and hunker down until 2012, like the Clinton administration did after the Gingrich Revolution, defending government from the worst excesses of those who would like to eliminate it altogether.

There’s only one problem with this scenario: the time-frame. Politicos and pundits are used to thinking in two-year cycles, and it’s easy to convince oneself that, in 2012, Obama will be able to capitalize on an improved economy, favorable voter-turnout patterns, and a weak GOP presidential field in order to sweep into office with a renewed mandate. But that misses a big part of the picture. Even if Obama wins reelection by a comfortable margin, it’s most likely that the House will remain in Republican hands and Democrats will lose seats in, and perhaps control of, the Senate—and beyond that, Republicans will probably do fairly well in 2014. In other words, we could be looking not at two years of damage control, but six.

Consider the Democrats’ congressional prospects in 2012. Republican successes at the state level during the past two years have given the GOP an extraordinary advantage in the decennial redistricting process. They control the governorship and both houses of the state legislature—known casually as holding the “trifecta”—in 20 states, compared to ten for Democrats. They’ve achieved this trifecta in six of the eight states that will gain representation in the 2012 round of redistricting. (As well as in three of the ten states that will lose seats, compared to two for Democrats.) While Republican gerrymandering will be restrained by rules mandating a “nonpartisan” redistricting process in some states, such as Arizona and Florida, as well as provisions in the Voting Rights Act, this will still provide them with a far-reaching advantage. Control over so many state houses and legislatures puts them in a strong position to shore up the marginal seats they just won in states like Texas, Ohio, Pennsylvania, Michigan, Alabama, Georgia, Tennessee, and South Carolina—as well as to destabilize Democratic incumbents who succeeded by narrow margins in places like Georgia and North Carolina.

We can’t be precise about how all of this will shake out. But it is reasonably clear that, to take back the House in 2012, Democrats would have to approximate the feat they pulled off in the banner year of 2006 while facing a changed and more hostile political map. Redistricting aside, a number of places where veteran Blue Dog Democrats lost in 2010—including three in Tennessee, two in Mississippi, and one each in Georgia, Florida, South Carolina, and Alabama—are heavily Republican districts that are very unlikely to flip back in the foreseeable future.

The Senate picture for Democrats in 2012 is not much better, for the simple reason that 23 of the 33 seats that will be contested then are currently held by Democrats, reflecting the 2006 landslide. To put it another way, Republicans could lose Senate races by a 19-14 margin and still recapture the chamber (or by a 20-13 margin if they win the White House). Meanwhile several Republican senators, including Orrin Hatch of Utah, Dick Lugar of Indiana, Kay Bailey Hutchison of Texas, and Olympia Snowe of Maine, will go into the 2012 re-election cycle more worried about right-wing primary challenges than about general election contests.