Gerrymandering, the creative drawing of political boundaries by one party in order to perpetuate its power, is one of the most durable expressions in the American political lexicon — with its origin almost exactly two centuries ago. In 1812, Gov. Elbridge Gerry of Massachusetts, a signer of the Declaration of Independence and later James Madison’s vice president, signed a bill redrawing the state legislative district map with some contorted shapes intended to favor his own party, the Democratic Republicans, even though the rival Federalists were dominant in the state.

One district in particular looked like a salamander, and Gerry’s opponents quickly coined the new term to ridicule the political “creature” the governor had endorsed.

The objective then was the same as the one so frequently employed now: When one party is clearly in control of drawing the lines, it works to improve its odds in as many elections as possible by carefully distributing a critical mass of its supporters in as many different districts as it can — and then packing the opposing party’s reliable voters into as few districts as possible.

The alternative, generally employed when neither party has clear control of the mapmaking process, is to settle for a sort of sweetheart deal that protects the political security of the incumbents on both sides of the aisle.

What’s not at all clear now is whether one party will dominate redistricting and have the latitude to go for broke, or whether each party will control maps with comparable numbers of seats, giving the process more of a play-it-safe mood. That’s because, 48 weeks from Election Day 2010, the political climates in the states are far from fully formed, and so it’s too soon to predict the overall winner of the campaigns for the governors’ mansions and statehouse gavels.

To maximize their chances, each party has a related organization — the Republican State Leadership Committee and the Democratic Legislative Campaign Committee — to provide advice and money to state legislative candidates. The Democratic group plans to spend $20 million or more, and the GOP group plans on spending as much as $22 million on such 2010 races.

“If we don’t win these state elections and have majorities, then the whole rest of this is irrelevant,” Carrie Cantrell, a spokeswoman for the Republican State Leadership group, said of redistricting.

The problem for both of these organizations is that it’s historically difficult to get even their most avid faithful excited about midterm state elections. “The great beauty of midterm races is that it becomes much easier for our races to command attention” compared with presidential election years, said Matt Compton, a spokesman for the Democratic Legislative Campaign group. “But it also makes it harder for us to make the argument to voters about why they should go to the polls.”

It is even more difficult to engage the interest of the party rank and file in redistricting — a topic that in most states comes up only once a decade, and is the kind of political process issue that tends to make the average voter’s eyes glaze over.

Parties Eye Their Options

One way to think of the redistricting power game is to imagine three tumblers in a slot machine labeled “Governor,” “State Senate” and “State House.” If all three in a state display either a Democratic donkey or a Republican elephant after Nov. 2, 2010, that party should be able to gerrymander at will — subject to the inevitable lawsuits the out-of-power party is bound to file. But if the display in the post-election window is split, the parties must either reach a compromise, which strongly favors incumbent protection, or else deadlock, which generally means the map is drawn by judges in the state or federal courts.

Thirty states where the chief executive has a role in enacting a congressional map will elect governors next year. There will also be state House elections in 35 states and state Senate contests in 33 states where the legislatures take part in making the maps.

If redistricting were conducted today, the Democrats would have the clear overall advantage. That’s because the same surge that boosted the Democrats to control of Congress in 2006 and the White House in 2008 also produced major gains in governor’s offices and state legislative seats.

The Democrats currently hold the governor’s office and majorities in both state legislative chambers in 15 states, which combined are on course to have more than a quarter of all the House seats in the next decade. The Republicans are similarly dominant in five states that now have 79 seats among them, although that group — Texas, Florida, Georgia, South Carolina and Utah — is projected to gain a combined eight seats in the reapportionment that will happen next year once the population results from the census are in.

But the partisan balance of power could be upended in many of those states next November. Republicans plan to take strong shots at the governorships in seven states dominated by Democrats — Colorado, Illinois, Iowa, Maine, New York, Oregon and Wisconsin — and perceive chances in Maryland, New Hampshire and New Mexico as well. And the GOP is intensely eyeing the state capitols in Wisconsin, where a gain of two seats would give them control of the state Senate and a four-seat switch would deliver the state House, along with the Colorado House (where the party needs a gain of six for a majority) and the Iowa House (where a gain of seven would do it.)

The Democrats appear to be most intensely interested in Texas, which is the second most-populous state (after California) and is also likely to be awarded four more seats in reapportionment, for a new total of 36. That would certainly require a sweeping overhaul of the state’s congressional map. And while the Texas GOP at the moment holds all three levers of redistricting power, it holds one of them, the state House, with just two seats to spare, while next year’s governor’s race could be one of the most contentious in the nation.

For the Democrats, winning the ability to at least help shape redistricting in the state would be especially sweet, because Texas represented one of the party’s biggest setbacks — and one of the GOP’s most audacious triumphs — in the current decade.

The original map for the state, drawn by federal judges because a politically split Texas Legislature couldn’t agree on its own plan, resulted in the election of 17 Democrats and 15 Republicans in 2002. But that election also gave the GOP control of the legislature as well as the governor’s mansion. And soon after, the party — under the guidance of Tom DeLay, who was then House majority leader — remade the map so that the 2004 elections sent 21 Republicans and 11 Democrats to Washington.

The Democrats went to court, arguing the new map was such an egregious gerrymander that it should be ruled unconstitutional, but the Supreme Court disagreed, with the exception of one district. Today, the GOP still holds a 20-12 advantage in Texas.

Big States in the Balance

Both parties also have reason to worry about their prospects in a populous state — California for the GOP, Pennsylvania for the Democrats — where a plausible switch of the metaphorical slot machine tumblers would give the opposing party complete control.

In Sacramento, Democrats have a solid hold on both halves of the legislature and are favored at this point — mainly by virtue of the state’s recent voting trends — to claim the governorship next year, when Republican Arnold Schwarzenegger is barred from seeking another term. Leading strategists in the party, which now holds 34 of the state’s 53 House seats, believe a map could be drawn to spread the number of Democrats more widely and thereby make the nation’s largest congressional delegation even more lopsided to their advantage.

Harrisburg, at the same time, poses the biggest comparable worry for the Democrats. The GOP is very likely to hold the Pennsylvania Senate; it is in a tossup campaign for the governorship — Democrat Edward G. Rendell ’s two-term limit is up; and it needs a gain of just three seats to take over the state House. Democrats are hardly eager to allow the Pennsylvania GOP a do-over of the last decade’s prime example of When Gerrymanders Go Bad.

Republicans controlled state government at the start of this decade and went after a good-old-fashioned gerrymander, crowing that their map — which had two fewer House seats than in the 1990s because of reapportionment — was drawn so artfully that it would establish a decade-long GOP dominance of the House delegation. And it worked, at least initially. Although the 2000 election had sent 11 Republicans and 10 Democrats to Congress, both the 2002 and 2004 elections sent 12 Republicans and just seven Democrats.

But the map has failed the party since then. The national Democratic tide was strong enough in 2006 to sweep out one GOP incumbent from a politically competitive district in the Pittsburgh suburbs (Melissa A. Hart) and another from a tossup district in the Philadelphia suburbs ((Michael G. Fitzpatrick), while two more Republicans (Curt Weldon and Don Sherwood) were defeated mainly as a consequence of their own ethical troubles. The symbolic coup de grâce came in 2008, when another Democratic surge swept out one more GOP veteran (Phil English) — who, ironically, had previously been in charge of the House GOP incumbent-retention political operation. And so today the Democrats have a 12-to-7 advantage in the state, precisely the reverse of what the map was designed to produce.

The lesson going into the next round of redistricting, experts say, is clear: A party that gets too greedy, and spreads its base vote too thin among too many districts, runs the risk of failing to provide its congressmen with enough of a reservoir of partisan support that they can withstand either a spate of scandal or a political wave in the other direction.

It would be unfair to suggest that only the Pennsylvania GOP failed to heed that lesson for this decade. Republicans who ran the process in three other big states — Ohio, Michigan and Virginia — also drew maps designed to elect mostly Republican congressmen, but in each case the delegations are now mostly Democratic.

One thing, though, makes Pennsylvania stand out more than the others — and underscores how hard it is for the players to accurately predict the national and state-level partisan trajectory over the course of 10 full years. It was Pennsylvania where the Democrats, so outraged over what Republicans had done with the congressional map, went to court in an effort to persuade the Supreme Court to set some limits on political gerrymandering. Although the court upheld the state’s congressional map, five of the justices signaled — at least in theory — that someday they could see a map with such tortured cartography that it would deny some voters their equal protection rights under the Constitution.

Preparing for Anything

Altogether, the Democrats currently hold 258 House seats, or 59 percent of the total, a robust majority unequaled by either party since the Democrats had that same number of seats 16 years ago. That means the Republicans have an ultimate midterm election goal to gain at least 41 seats to return their party to the majority.

Whichever party wins control of the House next fall, rank-and-file Democrats and Republicans alike will take an intense interest in redistricting — a process that, quite literally, puts their professional lives on the line.

If the Democrats remain solidly in power, they are likely to advocate “a defensive posture” toward redistricting that focuses on shoring up their base of support in the seats they’ve taken away from the Republicans in recent elections, predicts Bruce Cain, a political scientist and redistricting expert who heads the University of California, Washington Center. Many of those seats are held by ideological moderates who have been able to win in districts that continue to vote Republican at the national level. Today almost one in five members of the Democratic Caucus — 49 total — represents a constituency that preferred John McCain for president in 2008.

But if the party suffers significant setbacks, or a loss of control, “it’s going to make for some hard choices” for the Democrats who remain in the House, Cain said. “The incumbents are going to want to shore up their seats. The leaders are going to be saying, we could get this one back if we just futz with it.”

Preparing the Democrats for any eventuality is an organization called Foundation for the Future, established by party activists and support groups in 2006 to help state Democrats lay the logistical groundwork for the next decade’s redistricting.

As for House Republicans, if their current bullishness about their prospects for big 2010 gains proves true, they will probably push a more aggressive — but, for some of them, potentially risky — redistricting strategy of spreading the GOP vote around. To that end, a new group not directly affiliated with the GOP was formed this summer, and dubbed Making America’s Promise Secure, to press for maps that would aid the election of conservatives to the House. The chairmen of the group’s board are former House Speaker Newt Gingrich and former Senate Majority Leader Trent Lott.

But a comeback surge by the Republicans, viewed another way, would represent nothing more than another arc in the rapidly swinging political pendulum — which could make the leaders of both parties wary about adopting overly aggressive strategies that might not succeed over the course of a full decade.

“When volatility goes up, it’s not only the incumbents that will be risk-averse and want safer districts. The seat-maximizing strategy for the parties is also to be risk-averse,” said George Mason’s McDonald. And Republican strategists, as much as their Democratic counterparts, will have to deal with the self-preservation instincts of their incumbents, who almost always are inclined to choose safety first when it comes to the boundaries of their own districts.

“When you start asking someone to go from a 75 percent Republican district to a 55 percent Republican district, they’re like, ‘Whoa, whoa, whoa!’” said Republican Rep. Lynn Westmoreland of Georgia.

A former state House minority leader who was involved in a series of stormy partisan redistricting battles back home, Westmoreland has been tapped by House Republican leaders to be the liaison to GOP members as their state delegations prepare for the next redistricting cycle. Rep. Mike Thompson of California has taken on a similar role for the Democrats.

Predicting the precise course of the partisan pendulum is a challenge, too, for those political technocrats in charge of generating the demographic and voting behavior databases that will inform both party’s redistricting efforts.

“Things have changed pretty significantly over the past three or four national election cycles,” said Bill Burke, a Democratic operative who directs the Foundation for the Future. And as for this month’s off-year election results? “We know something significant happened. At this point, we don’t know exactly what.”