Beto O’Rourke and John Cornyn were not often on the same page during the six years that they both represented Texas in Congress. But for a brief moment, O’Rourke—then a Democratic congressman from El Paso and now a 2020 presidential hopeful—got the powerful Republican senator behind him in his quest to stop the federal government from building a wall on the U.S.-Mexico border.

The effort ultimately proved for naught, as a barrier ended up being built at the contested site. But O’Rourke’s successful wooing of the No. 2 Republican in the Senate could prove to be an asset as he goes about pitching himself to primary voters: proof that on Donald Trump’s signature issue, he not only has spent years crafting his position but also has some bipartisan credibility to bring to the debate.

The collaboration with Cornyn came in 2013, as U.S. Customs and Border Protection made plans to build a $5.5 million, 17-foot high steel fence along a half-mile portion of the border in El Paso, a city that is separated from Mexico by the Rio Grande and, in most places, high steel walls. At the time, that type of barrier did not exist in this historic part of the city, where Spanish explorers first crossed the river north in 1598.

In El Paso, officials were concerned that building the wall would hamstring efforts to revitalize the area, which had struggled since a huge freeway went up, separating it from the rest of town. The site’s supporters wanted to preserve its history and possibly develop it into a tourist destination—the Southwest’s answer to Plymouth Rock.

According to a report from El Paso Inc., the city let O’Rourke, then a freshman congressman, lead the charge to get CBP to back down on the wall. In November 2013, he sat down with Cornyn, Texas’ senior senator and the second-ranked Republican in the Senate, who has long championed border security measures.

After meeting with O’Rourke, Cornyn wrote a letter to Thomas Winkowski, then acting commissioner of CBP, encouraging him to listen to the congressman. “I understand that the project is near significant cultural and historical sites, and I would strongly encourage you to work closely with the El Paso community to ensure preservation of sensitive areas,” the senator wrote.

O’Rourke and five additional House members wrote a letter to Winkowski the day before saying: “Preserving the historic significance of this area should be our first priority and we strongly believe that a compromise can be reached.”

The lawmakers noted that El Paso had just been named the safest city in the country for the third year in a row. “It seems that there is little need to construct additional fence from a safety perspective when taxpayer dollars could be used more effectively in other areas of the border,” they wrote.

Meanwhile, CBP officials insisted that construction of a wall would not harm the area’s cultural and environmental resources, nor its economic value.

Representatives for Cornyn and O’Rourke did not tell The Daily Beast what ultimately came of their moment of cooperation. In May 2014, the El Paso Times reported that O’Rourke was still railing against building the wall in this section, but he admitted during a congressional hearing that federal officials were moving forward with the project.

The border now tells the tale: a high, see-through steel fence runs through the area, like it does through the rest of El Paso. Local officials have tried to secure grant money from the National Parks Service to spark development of the site and are awaiting approval. For now, the abandoned swath of land is gathering dust between the freeway and the border wall, listed by a Texas nonprofit as one of the most endangered historic sites in the state.

In the years since they cooperated, the border wall has become a central issue for both O’Rourke and Cornyn. O’Rourke—who passed up challenging Cornyn in 2020 to run for president—has said he wants to tear down the entire border wall in El Paso. When President Trump went to El Paso in February to rally for his immigration agenda, O’Rourke staged a counter-rally.

Cornyn, meanwhile, has become an ally of Trump and largely supports his immigration agenda. He has said in the past that there are parts of the border where it makes no sense to have a wall. But he has also backed the president’s emergency declaration to siphon money from other departments to finance construction of a wall along the southern border.

Cornyn’s office did not return a request for comment.