Democrats picked up their 30th seat in the House of Representatives last night. In a major upset, Democrat Ciro Rodriguez defeated Republican incumbent Henry Bonilla in a runoff election in Texas’s 23rd district. Rodriguez had previously lost two primaries to conservative Democrat Henry Cuellar, in ’04 and ’06. The third time around, he managed to defeat a conservative Republican.

In an odd way, Rodriguez has Tom DeLay to thank for his victory. DeLay controversially redrew the district in 2002, booting out 100,000 Hispanics to make it more Republican-friendly, giving Bonilla a safe seat. This summer the Supreme Court found that DeLay’s scheme violated the Voting Rights Act and forced the state to include a larger Hispanic population, boosting the Democrats chances. When Bonilla failed to receive 50 percent of the vote in the November 7 election, he moved into a runoff with Rodriguez.

Democrats knew they had a strong pickup opportunity, albeit very much under the radar. The Democratic Congressional Campaign Committee spent $1.5 million on the race. The National Republican Congressional Committee, by contrast, didn’t drop a dime. Bet they regret that now.

Moreover, the election proved just how much the Tom Tancredo wing of the Republican Party turns off Hispanic voters. Bonilla was the only Mexican-American Republican in Congress–and an aggressive proponent of hardline immigration measures. This election, usually supportive Hispanic voters deserted him in droves. “Bonilla’s loss last night confirms one of the Bush administration’s greatest fears,” the Hotline writes, “that a hard-line position on illegal immigration could cause Republicans long-term damage among the growing Latino vote.”