WASHINGTON — Along the 2,000-mile border with Mexico, which sprawls across four states and nine House districts, a single seat is held by a Republican: Representative Will Hurd of Texas.And Mr. Hurd, a former undercover C.I.A. officer who barely won re-election in Texas’ 23rd District, the largest of the nine, has emerged as perhaps the most persistent critic in his party of President Trump’s wall.Drawing upon his years undercover and his work in the private sector, Mr. Hurd has a starkly different vision for the southwestern border: fiber optic cables, sensors, radar, drones, increased staffing — but not the concrete or steel barrier that Mr. Trump has demanded before he reopens the government.He has joined Democrats eight times this month to vote to reopen the government, without wall funding.“Nobody likes being the cheese that’s standing alone,” Mr. Hurd said in an interview with The Daily, The New York Times’s podcast. “I have a unique perspective because I have so much border, because I have an entire career dealing with these issues. That is more important than any kind of political calculation.”“My specific role has always been to articulate the problems to a level of specificity that people can understand and then give the on-the-ground perspective and experience on what the solutions can be,” he added.Specificity, in this case, lies in the architecture of what Mr. Hurd describes as a “smart wall,” a wish list of technology and upgrades that would protect more than 800 miles of the southwestern border that demarcates the southern side of his district. He would dispense with the concrete wall or steel slats that Mr. Trump has advocated in raucous rallies, in favor of more advanced measures, including “a fiber optic cable from sea to shining sea.”“Let’s make sure we’re using the right tool in the right place,” Mr. Hurd said. “We should be thinking about all these different technologies and how they should be used, and when I describe this, nobody disagrees.”He added, “A wall from sea to shining sea is the most expensive and least effective way to do border security.”He is not, as his staff readily acknowledges, inclined to broadcast his perspective or obsessively rope in votes for his cause. He has not sought opportunities to directly lobby the president to endorse the technological barriers he has envisioned. (Mr. Hurd noted that the “key players” are all cognizant of his position.)Instead, he is content to remain on the periphery of the House Republican Conference, educating his colleagues, extending invitations to visit the border and voting the way he believes the majority of his constituents want him to. That is what resonates in a district that encompasses a large population of cybersecurity professionals — parts of San Antonio and rural areas — and has flipped five times between the two parties since the early 1990s.“My boss is not the president,” Mr. Hurd said. “My boss is not the speaker. My boss is not the minority leader. My bosses are those 800,000 people that I represented and sent me up here.”Aides say he often requests analysis of his personal outreach, including social media data and telephone town halls, that quantify who is following his work and their responses — metrics that inform his support of legislation on Capitol Hill, regardless of the party line or pressure from the presidential Twitter feed.“You can’t take a vocal minority as an indication of the epicenter of where people feel,” Mr. Hurd said. The mix of Republicans and Democrats in his district, he said, “believe that we should be able to secure our borders, and they think that’s a mix of tools that is necessary to do that.”His ability to deftly navigate the electoral perils of his district and retain a place on Capitol Hill has surprised both his party allies and his opponents across the aisle. His margin of victory in November was so slim — a little over 1,100 votes — that Mr. Hurd’s Democratic opponent attended new member orientation before conceding to Mr. Hurd.“I don’t know what it is, but it is clearly working for him,” said Colin Strother, a Democratic strategist in Texas. He added, “I’m sure among Republicans, there are people who aren’t happy that he’s not on board.”Conservatives acknowledge that Mr. Hurd is an asset to their conference; he has secured a temperamental electorate for now, and his intelligence, experience and status as the lone black Republican in the House chamber make him invaluable.“He just approaches it differently than most members,” said Matt Mackowiak, a veteran Republican strategist in Texas. “He’s also given the benefit of the doubt because of how difficult that district is.”Regardless of ideological differences, most Republicans express respect for Mr. Hurd’s knowledge, work ethic and dedication to the people he represents. In an announcement naming Mr. Hurd as a new member of the influential House Appropriations Committee, Representative Kevin McCarthy, Republican of California and the minority leader, hailed him as “one of the most innovative and entrepreneurial members” in Congress. Democratic colleagues hear a border security solution that resonates with their own border constituents.“He knows what he’s talking about,” said Representative Juan C. Vargas, a Democrat whose district traverses the California-Mexico border. “He hangs on because he’s smart and knows security.”Representative Pete Aguilar, Democrat of California, first reached out to Mr. Hurd to collaborate on legislation last year that would have secured a path to citizenship for so-called Dreamers, young undocumented immigrants brought to the country as children, while enhancing border security. The two men now text with each other so frequently that Mr. Aguilar jokes that his wife is a little jealous of their friendship.“Even members of Democratic leadership really respect how supportive he is in finding a solution on this issue,” Mr. Aguilar said.“It’s not lost on anyone on our side of the aisle,” he added, about how Mr. Hurd has crossed party lines to support bipartisan ideas on immigration and rebuff the president’s demands for a wall at the border.