In the heat of the Democratic presidential contest, Illinois Sen. Barack Obama and New York Sen. Hillary Clinton held their final debate at Cleveland State University. But that same night, Democrats in New York took a step closer to a goal that has eluded them for two generations: retaking the Empire State Senate.

When Assemblyman Darrel Aubertine, a Democrat, beat Republican William Barclay to fill the remainder of an unexpired term in the state's Senate, Democrats reached 30 seats in the chamber, just one shy of the Republican majority (the Democrats subsequently lost a vote in the chamber when newly appointed Gov. David Paterson vacated the post of lieutenant governor.) Since New York state senators have two-year terms, every one of the 62 Senate seats are up in 2008, and again in 2010. And while the outcome of the presidential contest will likely affect at most four sets of congressional elections in New York, a new Democratic  majority in the New York state Senate-and in a few other state legislatures-could determine the partisan makeup of Congress for a generation or more.

There are more than 7,200 state legislative seats around the country. As with Congress, many legislatures are held by narrow majorities of one party or the other, and, like the U.S. House, are susceptible to national waves. In 2006, when Democrats won back 30 seats in Congress, the party also added a whopping 300 seats in state legislatures across the nation. Those legislators, and those chambers, set policy that frequently has more impact on someone's daily life than Congress does.

But strategists in Washington know that control of the chambers is crucial for another reason: In 36 states, legislatures play a major role in redistricting, and will draw new boundaries at both congressional and state legislative levels after the 2012 reapportionment of House seats. "State legislatures are the battleground for the upcoming congressional races for the next decade," says Michael Sargeant, executive director of the Democratic Legislative Campaign Committee. "They've been [battlegrounds] for this decade, and they will continue to be."

A shift of only a few seats in a few states could hand the power to draw the map to a member of a different party-potentially shifting dozens of seats and either solidifying the Democratic majority or giving Republicans a chance to reclaim the Speaker's podium that much faster. Sargeant points to the 2002 redistricting, which left Democrats at a distinct disadvantage in Michigan, a generally Democratic state, and to the mid-decade redistricting in Texas, after which half a dozen Democrats lost their seats, as examples of what redistricting can do to a party.

Texas is rare, though. "There aren't a lot of Texases left," says DLCC spokeswoman Alex Dery Snider. "It's going to be death by a thousand cuts." She points to a number of states where only one or two congressional seats might be vulnerable.

In all, the DLCC counts 17 congressional seats that changed hands after the 2002 redistricting. While Republicans are perceived to have "won" redistricting cycles in 1992 and 2002, netting more seats than Democrats, the effects have been limited, says George Mason University professor Michael McDonald. "What happens in one state can cancel out what happens in another state," says McDonald, an expert in voter turnout who consulted for Arizona's bipartisan redistricting commission in the last cycle. "The opportunities for one party to beat the other is kind of muted by federalism."

Last time around, Republicans looked to benefit. This time out, thanks to the national political landscape, the pendulum seems to be swinging in the Democrats' direction. "2008 is another interesting political year for us," says Carrie Cantrell, spokeswoman for the Republican State Leadership Committee. Still, her party sees opportunities if GOP candidates for local offices focus on more local issues. "The candidates who ran a local race [in 2006] and didn't get bogged down in national issues were able to defeat the odds," she notes.

Carving a Majority

States redraw their congressional and legislative maps, generally speaking, in one of two ways: Either the legislature draws a map, opening the door for partisan gerrymandering, or a bipartisan commission takes up the matter. Some commission states have maps featuring competitive districts; in Arizona, for example, four of the eight districts are said to be competitive. In 2006, Democrats won two of those seats, while this year the party is favored to pick up another, that of retiring GOP Rep. Rick Renzi.

Other commission states, though, draw maps that are less competitive. In Washington state, for example, no incumbent member of Congress has lost since 1998, and no seat has changed hands since 2000. "Usually, you get a bipartisan map produced," says McDonald, who argues for a balance between competitive districts and those that are safe for one party or another. "Do you really want to have a legislature that's set in stone for a decade, or do you want a legislature that is at least moderately responsive to the public mood?"

In states where legislators draw the lines, parties battling for control of a seat here or there are playing for longer-term advantage. Unlike in Texas, which proved a huge windfall for Republicans, most of these redistricted states will see a maximum of perhaps a three-seat shift. The goal, say strategists from both parties, is to find states where redistricting could change a seat or two at a time, on the way to larger congressional majorities. "We focus on winning as many Republican seats as possible," says Cantrell. "And the byproduct of that is having Republican majorities there for when redistricting gets done."

In this high-stakes national chess game with 7,200 pawns, there are multiple ways to win.

The first way is to draw a new seat that is tailor-made for one's party. Reapportionment begins when some states grow at a faster pace than others. In the past decade, population has shifted from the Northeast and the Rust Belt to the Sun Belt. The 2010 census is expected to show big population gains in states like Florida, Texas, Georgia and Nevada, all states where legislatures redraw district lines. Consequently, those states will earn extra members of Congress-in all likelihood, three for Texas, two for Florida and one each for Georgia and Nevada. California and Utah are also expected to win new delegates to Congress.

All those state legislatures will have a say over how the new districts are drawn. California, which has a long history of drawing as many non-competitive districts as possible, will likely create a seat ripe for the Democratic taking-the party enjoys a wide 10-seat advantage in the 40-member Senate and a 15-seat head start in the 80-seat Assembly, along with one vacancy. Utah, on the other hand, will probably carve out a safely Republican seat, as both the Senate and House are firmly in GOP hands, giving them the chance to draw the map.

But in Nevada, Democrats hold a 12-seat majority in the 42-member House and are just one seat away from re-taking the state Senate, where Republicans hold an 11-10 majority. If Democrats can take back one or more seats, their experts will redraw congressional and legislative lines. The battle for the state House and Senate, Cantrell and Sargeant say, is a high priority for both the DLCC and the RSLC.

When the state picks up a seat, instead of taking voters from the heavily Republican 2nd District in the north, Democrats can manipulate the map in such a way as to take their voters out of Rep. Shelley Berkley's safely Democratic Las Vegas-based seat to form the backbone of a new district. Berkley will still win reelection, though perhaps by a slightly smaller margin than in 2006, while another Democrat could represent the Silver State in Washington.

New York's Senate is so important to both parties because of the second way to win: Since New York's growth has failed to keep pace with the rest of the country's, over the last seven decades the state has seen a marked drop-off in congressional representation. In 1930, New York elected 45 members of Congress. After the 2002 reapportionment, it elected just 29. In 2010, the state will likely be informed that it is losing another two seats, bringing its vote total down to 27. Representatives from the Assembly speaker's office, the Senate president's office and the governor's office will draw new congressional and legislative maps together. In 2002, Gov. George Pataki and Senate President Joseph Bruno, both Republicans, had to reach a compromise with Assembly Speaker Sheldon Silver. Today, the political situation is tougher for Republicans, and the state Senate, along with the 2010 governor's race, will determine whether Democrats have all the influence over map-making or if Republicans can squeeze a foot in the door.

States in the Balance

If Democrats retake the New York state Senate and hold onto the governor's mansion, they alone will control redistricting. With the state losing two seats, they can redraw any-or all-of the six Republican members of Congress into districts less suited for them, in any one of several ways. Democrats might place two incumbent Republicans in the same district; that happened to Michigan Democratic Reps. John Dingell and Lynn Rivers in 2002 when their state lost a seat.

New York Democrats could also draw some of the state's Republican congressmen into districts more favorable to a Democratic incumbent. GOP Reps. Peter King, of Long Island, and Vito Fossella, of Staten Island, are completely surrounded by Democrats, while upstate Reps. John McHugh, Jim Walsh, Tom Reynolds and John "Randy" Kuhl represent moderate districts, at best. Perhaps reading the writing on the wall, Walsh has announced his retirement at the end of this year, and by cycle's end more may join him, willingly or not.

Illinois, Louisiana and Minnesota, where state legislatures are all easily controlled by Democrats, will each lose a seat, and legislators are likely to draw a Republican out of his or her home district. Democrats will likely fare poorly in Missouri, which will lose one seat, and Ohio, which loses two; in both places, the party has little hope of overcoming wide Republican majorities.

Massachusetts, where Democrats have a wide legislative majority, will also lose a single member, though its 10 congressmen are all Democrats.

In the race to sabotage an incumbent, the battlegrounds will be in Pennsylvania, Indiana and Michigan. In all three cases, Democrats control the state House by a narrow margin but trail Republicans in the state Senate.

Indiana could be especially volatile, thanks to the third way to claim victory after 2012. Democrats knocked off three Republican congressmen in 2006 and won a narrow two-seat majority in the state House, putting a giant target on their own backs. Should the GOP win control of the chamber and keep the governor's mansion in this year's election, they will be able to redraw boundaries around those three new incumbents, all of whom represent districts that otherwise vote Republican. With control of the state House, Republicans could just change the map.

Democrats have their opportunities as well. In Colorado, where the party has made impressive gains, Democrats now control the legislature and the governor's mansion. GOP Rep. Marilyn Musgrave has faced several heated challenges in recent years, though she has thus far managed to survive. If Democrats draw a few more of their voters into her district, they might finally defeat her. Republican incumbents in Illinois and Minnesota could also face redrawn districts that present them a larger challenge.

One challenge several state legislators also must consider, McDonald points out, is compliance with Section 5 of the Voting Rights Act. That statute requires certain states to submit their plans to the Justice Department in order to protect the rights of minorities. The resulting districts, which may be majority-Hispanic or majority-African-American, can help Democrats by guaranteeing them a seat, though they can hurt the party by concentrating a large portion of the base in one district instead of spreading it among several.

Sixteen states currently face Section 5 requirements. Interestingly, since implementation of the act in 1965, Republicans have held the White House in every redistricting cycle, and therefore have controlled the Justice Department. Should Obama or Clinton take the White House, the Democratic Justice Department would be able to manipulate maps, if only slightly-something McDonald suggests could net the party a few extra seats.

Thanks to confusing rules which vary by state, the redistricting outlook is far from clear. But both parties have experts in Washington paying close attention to outcomes of hundreds of local elections across the country.

State legislative elections in each of the next three years could prove hugely beneficial for one party or the other, not only in terms of local policy but also because of the larger implications. Depending upon which side is able to capitalize on myriad opportunities throughout the nation, the very shape of Congress could be altered for the next decade, or longer.

Reid Wilson is associate editor at RealClearPolitics.com, and hosts Politics Nation on XM Satellite Radio Saturday mornings.