Former Rep. Ciro Rodriguez (D-Texas) and Texas state Rep. Pete Gallego (D) are headed to a runoff after neither cracked the 50 percent threshold Tuesday night.

Rodriguez led Gallego by 46 percent to 40 in the first round of voting. The two will face off in a late July primary for the right to take on vulnerable freshman Rep. Francisco "Quico" Canseco (R-Texas), who narrowly defeated Rodriguez in 2010.

While Rodriguez had higher name identification and is better-known around the district, Gallego had the backing of the Democratic Congressional Campaign Committee, and the League of Conservation Voters, an environmental group, spent heavily on his behalf.

The real winner of the night could be Canseco, since his eventual opponent will now be forced to spend the next two months focused on the runoff rather than saving his resources and pivoting to the general election. The race in the swing district, which stretches west from San Antonio almost 1,000 miles to El Paso's outskirts, will likely be the most competitive in Texas.