“If you ask me this is all about politics,” said Mr. Gonzalez, adding that he was a disabled Army veteran with post-traumatic stress disorder. “The Democrats want illegal immigration because that means more votes for them.”

“But I took an oath to protect my country and what’s happening on the border is an invasion threatening our people,” said Mr. Gonzalez, who is planning to sleep in his 2001 Chevrolet Suburban. “These men are patriots and I'm proud to stand alongside them.”

Mr. Gonzalez, who was carrying a 9-millimeter handgun in a holster strapped to his belt, said he considered himself part of the militia. But the two other men at the spartan camp said they didn't think Mr. Gonzalez was part of their group.

“He just showed up today,” said the man called Viper.

At one point on Tuesday, there were more reporters milling about the camp than militiamen. Some of the journalists broadcast in Spanish to reach viewers on both sides of the border.

Judith Sierra, the owner of Tortilleria Sierra in Sunland Park, chuckled at the thought of armed men traveling to the border to chase after women and children. It’s not uncommon for migrants to pass through her property, she said, lately in large groups.

“We offer them water or tortillas,” she said, adding that the Border Patrol is never far behind.

“Even with a fence or whatever else it’s not going to stop people,” said Ms. Sierra, who was attending to a steady stream of customers in a black apron dusted with flour. “They’ll come over or under, somehow, they’ll find a way to cross.”