* Republicans seeking to hold onto 2010 gains in House
* Texas, North Carolina, Illinois focus of major disputes
By Jeremy Pelofsky
WASHINGTON, Aug 18 As President Barack Obama and Democrats fight to take control of the U.S. House of Representatives in 2012, legal battles are erupting in states where Republicans are tilting voting maps in their favor.
In states such as Texas and North Carolina, Republicans who control legislatures are redrawing the boundaries of voting districts to tighten their grip on seats in Congress and are trying to minimize the chance that Democrats could steal them away.
Obama's Justice Department or federal courts will have to approve some of the maps under a 1965 civil rights-era law. Democrats and some minority groups already have filed lawsuits arguing the redistricting maps unfairly marginalize them.
The stakes are huge with tax and spending policies atop the agenda. When Democrats last controlled Congress and the White House, healthcare and financial regulation reforms passed.
Democrats will require a major political shift to regain control of the House, which they lost in a nationwide vote a year ago. Come the November 2012 elections, they will need a net gain of 26 in the House where all 435 seats are at stake.
"I do not see the Republicans as increasing their lead in the House of Representatives because of the redistricting cycle, but they should be able to shore up their vulnerable incumbents," said Nathaniel Persily, director of the Center for Law and Politics at Columbia Law School.
States are assigned House seats based on a national census, last conducted in 2010. States that lean Democratic, like New York, lost seats as the population shifted toward more conservative regions, including Texas, Florida and Arizona.
The shifts are leading to fierce legal battles over the new lines that states drew for the congressional seats with both sides accusing each other drawing them based not just on race but on politics, a process called gerrymandering.
Those lawsuits may be tougher to win according to David Wasserman who monitors House races for The Cook Political Report. "There is no clear bright line to identify what constitutes partisan gerrymandering or not," he said.
CARVING UP TEXAS
Perhaps no state illustrates the controversy better than Texas, which received four new congressional districts thanks to a rapidly growing Hispanic population that would appear to favor Democrats.
But, Republicans control the legislature and the governor's mansion so they sliced up the map to improve their electoral chances, creating only one new heavily Hispanic district.
"There's one more Latino district than there was in the last cycle, but boy that doesn't reflect where all the growth came from," said Justin Levitt, an associate professor at Loyola School of Law in California.
Court documents filed in Texas have shown how Republicans discussed dividing up voting precincts to try to build support in their districts, and in one case trying to include apartment buildings full of their supporters and a country club.
In creating the new majority Hispanic district, other areas on Texas' map were carved up to add more Republican voters to districts narrowly won by freshmen who rode the Republican wave to capture the House in 2010 like Representatives Francisco Canseco and Blake Farenthold, experts said.
Hispanic voters in the Dallas/Fort Worth area were split among several Democratic districts rather than given their own seat. Some have argued they should also have a district in the Houston area. As a result, they have filed lawsuits.
To address longtime racial discrimination, once endemic in the South, a 1965 civil rights law required some states, including Texas, to get approval for any changes to its district maps to ensure they did not harm minorities.
In a rare move, Texas officials filed a lawsuit in court in Washington for approval of the new map rather than going to the Justice Department, run by Obama appointees.
But the bigger battle will likely be back in Texas, where Hispanic groups have filed lawsuits in federal courts there challenging the map as discriminatory, Levitt said.
"The particular question here isn't going to be backsliding but whether Texas has done what it needs to do in order to address the current and growing minority population," he said.
Legal battles over redistricting often drag on for months, if not years. If a new map cannot quickly pass judicial muster, the courts could draw it, and that could hurt either side.
After the 2000 census, Texas went up against Washington over its redistricting plan after winning six House seats. The map was largely upheld by the Supreme Court.
Democrats are not the only ones challenging redistricting maps, Republicans have filed lawsuits in Illinois.
OBAMA FEARS SUPREME COURT CHALLENGE
Obama's Justice Department has been seen as hesitant to bring challenges against states because of fears the Supreme Court would strike down the part of the Voting Rights Act that requires some states to seek pre-approval for their plans.
"The Obama Justice Department if anything has behaved rather timidly and that is because they know the Supreme Court is chomping at the bit to strike down section five of the Voting Rights Act as unconstitutional so they are picking their battles wisely," Persily from Columbia Law School said.
A Justice Department spokeswoman, Xochitl Hinojosa, said they will challenge redistricting maps where local authorities cannot prove the changes will not impact "the right to vote on account of race, color or language minority status."
(Editing by Cynthia Osterman)