The 23rd District in Texas is a judicial creation two times over. The district was represented for over a decade by Republican Henry Bonilla, but in 2006 the U.S. Supreme Court declared that the 23rd violated the Voting Rights Act of 1965. A federal judge substantially increased the Hispanic population of the district, and Bonilla lost to Democrat Ciro Rodriguez (who had been upset in a primary by Henry Cuellar in the neighboring 28th District a few years earlier).
Rodriguez lost to Republican Francisco "Quico" Canseco in the 2010 landslide. The GOP attempted to shore up the district, which stretches across the vast, empty expanses of southwest Texas to cover the El Paso and San Antonio suburbs. But a federal court undid that effort, and actually made the 23rd a touch more Democratic than it had been in its earlier iteration.
The district still leans a bit toward the Republicans, and Canseco is still a Latino Republican running in a Latino district with a Republican PVI. But he faces a top-notch challenger in state Rep. Pete Gallego, who represented some of the more Republican areas of the district in the state legislature.