Washington ? Fast-growing Southern states could gain nine new congressional seats after the 2010 census, largely at the expense of their neighbors to the north, judging from the latest government data.

Georgia and North Carolina’s delegations in the U.S. House would overtake New Jersey’s, for example, while Florida would catch up with New York, according to projections based on a July 2007 population snapshot released by the Census Bureau last month.

Texas would be the biggest gainer, while a handful of Western states such as Arizona and Nevada could also grab new seats.

The power shift would continue a long-term trend and has been predicted for years. But the latest population estimates provide the clearest picture yet of the likely winners and losers.

With many of the growth states tilting Republican, the changes could influence the partisan makeup of Congress, although experts caution that the political ramifications are murky and depend heavily on how states divvy up the spoils.

“Right now what you can say is that you’ve got gains in areas that Republicans tend to do better in and you’ve got losses in areas that Democrats tend to do better in, so nationally … one would think Republicans would do better,” said Kim Brace, president of Election Data Services, a political demographics consulting firm. “But it depends on what happens in the next stage.”

The 435 seats in the House are divided among the states every 10 years based on the census. State legislatures are charged with drawing new congressional district maps, a process that often creates bitter partisan struggle. The reapportionment from the 2010 census will go into effect for the 2012 election.

The recent population estimates show that the South grew faster than any other region from July 2006 to July 2007, closely followed by the West.

Depending on what happens in the next few years, Texas could gain as many as four additional seats, according to projections from Election Data Services and Polidata, another national consulting firm. Florida could pick up two, while Georgia, North Carolina and South Carolina could add one each. Louisiana remains in danger of dropping a seat after population losses from Hurricane Katrina.

Arizona could pick up two seats, with Nevada, Utah and Oregon getting one each.

New York and Ohio could be the biggest losers, dropping two seats each, with Massachusetts, New Jersey, Pennsylvania, Michigan, Illinois, Minnesota, Iowa, Missouri and California possibly dropping one seat each.

On the surface, the projections look troubling for Democrats, who fare particularly poorly in the South and have done well in the Northeast and Midwest.

But political demographers say many of the growth states such as Florida and Arizona are increasingly competitive for Democrats. That trend could spread because much of the population increases in the South and West are coming from newcomers from Democratic-leaning states and from minority groups, particularly Hispanics.

“Conventional wisdom might be that growth in the Sunbelt means growth for Republicans, but I don’t think that’s necessarily the case,” said William Frey, a demographer at the University of Michigan and the Brookings Institution.