Rodríguez also dominated in Maverick County, home to the border city of Eagle Pass, while Bonilla did well in rural Uvalde and Medina counties west of San Antonio. The men were almost even in Val Verde County, home to Laughlin Air Force Base.
“No one would have predicted that Rodríguez would win this big,'' said Gary Keith, a senior lecturer in government at the University of Texas at Austin. “It's going to be read as a further vindication of Democratic strength in November and it may well be. But on the other hand it may be that there was a very strong get-out-the-vote effort.''
Encouraging partisan turnout was the refrain for both campaigns. Bexar County, the district's population anchor, extended its early voting period. While early voting tends to be Republican, Rodríguez carried the early vote.
Rodríguez said a last-minute visit from former President Bill Clinton that drew hundreds of supporters on Sunday provided an important boost to his campaign.
Keith said it’s possible voters also simply decided they would be better represented by a lawmaker in the majority party.
“That's often a card that's used in campaigns—whether one will be sidelined,'' Keith said.
Bonilla called Rodríguez Tuesday evening to concede, Bonilla spokesman Phil Ricks said.
Bonilla blamed the Supreme Court ruling that declared the district's former boundaries unconstitutional and forced a redrawing of the district that added more Latino Democratic voters.
“We just couldn't score again and again,'' Bonilla told supporters. ``But that's OK. This is a different time now. I can tell you I've had 14 years as a member of the House of Representatives and I count my blessings.''
The pickup for the Democrats in Congressional District 23 narrows Republicans’ margin in the state's congressional delegation to 19-13. Texas added one Democrat already in the suburban Houston 22nd Congressional District once held by Republican Rep. Tom DeLay.
Bonilla, the only Mexican-American Republican in Congress, nearly avoided the runoff when he came just shy of the 50 percent mark in a Nov. 7 free-for-all special election that included eight candidates. Rodríguez, in second place, advanced to the runoff with Bonilla.
Bonilla, who dismissed contentions that his support among Latino voters had eroded over the years, sought an eighth term in Washington, while Rodríguez now returns after a two-year absence. Rodríguez served from 1997-2005 in another district, but was ousted in the March 2004 Democratic primary by Rep. Henry Cuellar, D-Laredo. Rodríguez lost again to Cuellar in this year's primary for the 28th District.
Bonilla far outpaced Rodríguez in fundraising ability, but the Democratic Campaign Committee spent more than $870,000 in the runoff to boost Rodríguez's campaign.
The Supreme Court ruled in June that a 2003 reconfiguration of the 23rd District was unconstitutional because it diluted minority votes by splitting Laredo, a city that is almost all Latino, into two districts.
A three-judge panel redrew the district in August to restore 100,000 Latinos to the 23rd District that had been shunted elsewhere. The new district, which stretches from San Antonio south to the Mexican border and almost to El Paso in the west, gave Rodríguez yet another chance at national office and made Bonilla fight a little harder to keep his seat.
The new 23rd district has a voting age population that is 61 percent Latino, versus a 51 percent Latino voting age population before.
Rico de La Prensa contributed to this report.