NOGALES, Ariz. — Tony Estrada is the law here — not President Trump.

The well-worn crossing along the Mexican border is a place where President Trump’s strident campaign rhetoric aimed at Mexican immigrants still throbs. And few feel the sting more than the 73-year-old Santa Cruz County sheriff.

Born in neighboring Nogales, Mexico, Estrada arrived in the United States, at the age of 1, and now occupies the local public safety building that bears his name. His personal story is a familiar one in the dusty town that for decades has marked the beginning of thousands of hopeful immigrant narratives.

Yet this place and Estrada’s deep roots here underscore some of the most complicated issues confronting the Trump administration’s contentious efforts to secure the border, from a White House directive authorizing local police to assist with federal immigration enforcement to the proposed wall.

During the campaign, Trump often celebrated the endorsement of Joe Arpaio, the former Phoenix-area sheriff whose hard line on illegal immigrants foreshadowed the then-candidate’s border agenda. But just 179 miles to the south in Nogales, and all along the nearly 2,000-mile southwest border, Trump’s plans are playing to a much more skeptical, if not adversarial, audience.

Part of the Southwest Border Sheriffs’ Coalition, whose members are scattered across four states, Estrada and his colleagues are flatly opposed to the centerpiece of Trump’s plan: the wall.

"The wall is not the answer,'' said Sheriff Joe Frank Martinez, the coalition president whose own Texas county includes 84 miles of border with Mexico. Among the primary obstacles, Martinez said in a recent interview, the new administration has failed to reconcile complex environmental and cultural conditions inherent to the border that make such a massive undertaking (cost estimates have topped more than $20 billion) "impractical.''

And while Santa Cruz County (population: 46,000), represents perhaps the poorest stretch of the Arizona-Mexico border, Estrada's strong bi-national connections here have cast him as one of the most forceful and vocal opponents of Trump's unfolding border strategy.

Each time the new president refers to his plans for a "great, great wall,'' as he did most recently in an address before a joint session of Congress, the words re-open deep wounds first inflicted on many here during Trump's initial appearance as a candidate when he referred to Mexican immigrants as murderers and rapists.

"He insulted my people,'' Estrada said. "When he said that, I took it personally. That's not right. He shouldn't be talking about people like that, people you don't really know. If he knows them, he's probably had them doing his construction work.''