A federal three-judge panel dealt Republicans a major blow today in the Texas redistricting legal battle.
 
The judges drew a preliminary Congressional map that appears to protect incumbents and gives Democrats an edge in picking up three of the four new seats Texas gained in reapportionment. The plan increases the electoral potency of minorities in certain districts, giving an added boost to Democrats who tend to do very well among Latino and African-American voters.

The biggest individual winners are Rep. Lloyd Doggett (D) and state Rep. Joaquin Castro (D). The two were set to run against each other — based on a GOP-drawn map passed earlier this year that is now being litigated in court — in a district that ran from south Austin, hugged Interstate 35 and went deep into urban San Antonio. With the GOP-drawn map tied up in the courts, the interim map released today is likely to be used in the 2012 elections.

Under the court-drawn map, political observers believe Castro will run for a new seat based in San Antonio. Doggett will now likely run again in his current 25th district, which under the court redraw includes a large amount of friendly territory in his native Travis County.
 
In the state Legislature’s original map, the 25th was dramatically redrawn to favor Republicans. The candidate most likely to win that seat, former Railroad Commissioner Michael Williams, is one of the two biggest losers in the map released today.

The other big loser is former Texas Secretary of State Roger Williams (no relation). He was running in the 33rd district, one of the new seats that under the GOP map encompassed predominantly Republican parts of Tarrant County. The court-drawn version of the 33rd makes it likely a majority-minority district that includes urban, Democratic parts of Tarrant County. One Texas Republican expert on redistricting matters doubts either Williams will be going to Congress if the court-drawn map is implemented this cycle.
 
Two freshman Republicans will still have races to watch under the new map. Rep. Francisco “Quico” Canseco (R) is expected to see a competitive contest in the the 23rd district, while party operatives on both sides of the aisle said Rep. Blake Farenthold (R) is in deep primary trouble.

Farenthold, who currently represents the 27th district, is expected to run in the 34th district under the court-drawn map. The redrawn district includes an estimated 2 percent of his current district and extends to new territory in western Harris County, giving him a whole new population of constituents. Even before this new map was released, partisans suspected Farenthold, a surprise winner in the 2010 midterms, could be susceptible to a primary challenge. The new map only reinforces that perception.
 
Experts were reluctant to make specific projections about the partisan implications of this map because data is still being crunched. Texas Democratic redistricting expert Matt Angle offered a first-glance projection that Democrats could control 13 seats under the new map, compared with the 10 seats Democrats were projected to hold under the GOP-drawn map.
 
The new map is only a proposal. The court is seeking comments and objections until noon on Friday. It is believed that the court on Friday will issue a final map, which will be implemented for next year’s primaries. The Congressional filing period in Texas begins Monday and ends Dec. 12.

The decennial redistricting process, controlled by GOP-held legislatures in a number of key states, was expected to be a boon for national Republicans this cycle. While a number of marginal seats — especially in the South — have been shored up to protect GOP incumbents for years to come, Democrats have won key victories in a number of court cases.

The net number of seats gained or lost throughout redistricting was thought to be a wash over the last few months, giving neither party a particular edge in the 2012 race for control of the House. But with the Texas map appearing to give Democrats an edge and new maps in a number of big states still outstanding — including New York, Florida and Pennsylvania — the final outcome could end up giving one party a slight edge in picking up seats.

Joshua Miller contributed to this report.