TECATE, Calif. (AP) — Edgar Alexis Lopez looks well-rested in photos he took before crossing the border illegally in mountains east of San Diego, flashing a wide grin in clean jeans.

Six hours later, the 24-year-old Mexican construction worker was out of water, exhausted after climbing over the border wall and convinced he would faint. Abandoned by his smuggling guide, he and his father called for help.

A rescue helicopter couldn't land in the steep terrain, but authorities dropped water before border agents arrived and whisked them back to Tijuana, Mexico. Lopez quickly recovered and began planning another attempt to reach San Diego, where he hopes to earn a more steady living. He tried twice more in the following days, turning around before he got caught.

“You enter and leave, enter and leave, enter and leave,” Lopez said during a lunch break at his job in a Tijuana supermarket, where he was saving money for a fourth attempt. “You have nothing to lose besides the physical strain.”

After a slew of profound changes by the Trump administration to limit asylum, the coronavirus brought it to a halt. With immigration laws largely suspended at the border since March, Mexicans and people from Guatemala, Honduras and El Salvador who enter the U.S. illegally are immediately expelled without even a piece of paper, generally within two hours and with no chance to plead for asylum — the post-Holocaust system to protect people around the world from torture and persecution at home. Facing no consequences, migrants are more determined to keep trying until they succeed.

The suspension of asylum combined with the introduction of “express deportations,” as migrants call them, accelerated a shift in who is crossing the border illegally: more Mexican men who come for economic reasons and far fewer from Central America, Africa and elsewhere seeking asylum.

Dismantling asylum may be the most significant way President Donald Trump has reshaped the immigration system, which he has arguably done more to change than any U.S. president. He's thrilled supporters with an “America first” message and infuriated critics who call his signature domestic issue insular, xenophobic and even racist.

Before the election, The Associated Press is examining some of Trump’s immigration policies, including restrictions on international students, a retreat from America’s humanitarian role and now a virtual shutdown of asylum.

Under the rapid expulsions that began in March, 37% of those caught had been picked up in the previous year, up from 7% in the 2019 fiscal year. The annual figure hasn't topped 14% since the Border Patrol began keeping track seven years ago.

Recidivism hit 48% among Mexican adults over recent a two-week period in the Border Patrol's San Diego sector, said Chief Rodney Scott. Rates are highest in San Diego; El Paso, Texas; and Texas' Rio Grande Valley because large cities are on the Mexican side.

“They can get a night’s rest and try again,” Scott said in a recent interview.

To discourage repeat crossers, the administration has been flying Mexican citizens farther into the country — to Mexico City and distant provincial capitals. Mexican officials support the flights as a way to ease pressure on border cities like Tijuana.

A small group of Mexican men walked two days through brush and boulder-strewn mountains near Tecate, planning to take four days this month to reach Interstate 8, where a driver would take them to San Diego. But agents caught up and rushed them to the border crossing with Tijuana.

For Jose Luis Bello, 37, it was his eighth expulsion since March, having been flown to Mexico City once, and he's still determined to reach his U.S. citizen children in Columbus, Ohio. Jose Magana, 35, in the same group, was caught eight times in five months. He's been flown to midsize cities Villahermosa and Queretaro but is eager to return to Tijuana on his way to try to reunite with his wife and children in San Francisco.

“I'm still in for it 100%,” Bello said.

It is a throwback to the 1970s through 2000s, when Mexican men coming for jobs tried to evade agents. Asylum was almost an afterthought to policymakers until families — many from Central America — helped make the U.S. the world's top destination for asylum-seekers in 2017. Many simply surrendered to agents.

“It’s a little bit more of the revolving door than it used to be,” said Scott, the Border Patrol chief.

Asylum is for people fleeing persecution for their race, religion, nationality, political beliefs or membership in a social group. It isn’t intended for people who migrate for economic reasons.

Trump has repeatedly called asylum “a scam,” largely undoing it before the pandemic. He virtually ended the practice of releasing asylum-seekers in the U.S. with notices to appear in court.

“The single greatest threat to the integrity of U.S. borders is the tactic of lodging frivolous asylum claims for the sole purpose of gaining admission to the country,” Stephen Miller, a Trump senior adviser, told the AP. "A general policy of granting any person who shows up unlawfully at the border admission into the country and a work permit pending a future asylum hearing is not tantamount to open borders. It is open borders."

Critics say halting asylum, which is being challenged in court after Trump relied on a little-used public health law amid the pandemic, is a gross abdication of legal and moral obligations to protect people fleeing human rights abuses. Border Patrol agents may refer people for screening under the U.N. Convention Against Torture, but the bar is extremely high.

There were nearly 200,000 pandemic-related expulsions from March through September, but the administration's attack on asylum goes back to its early days, when thousands of parents were separated from their children to face criminal charges under a “zero tolerance” policy on illegal crossings. Other key orders:

— About 70,000 asylum-seekers from dozens of countries have been returned to Mexico since January 2019 to wait for court hearings. It's subjected asylum-seekers to extreme violence and made it even more difficult to find attorneys. Less than 1% have won claims, far below rates for all those seeking asylum.

Democrat Joe Biden has pledged to end the policy, called “Migrant Protection Protocols.”

— The administration struck agreements with Guatemala, El Salvador and Honduras last year for people to be flown to seek asylum there instead of in America. That's despite the U.S. State Department finding significant human rights abuses in all three countries, including violent targeting of minority groups.

From November to March, when the virus halted flights to Guatemala, only 20 of 939 Hondurans and Salvadorans sent there sought asylum in Guatemala. Nearly all went home.

Miller said Trump would seek similar arrangements with countries worldwide if he’s reelected, creating a global network that would spread asylum cases more widely.

— U.S. Customs and Border Protection late last year began keeping Mexicans and Central Americans in custody through initial asylum screenings, ideally done within three days. CBP facilities lack beds and other basics, and asylum-seekers face extraordinary challenges finding attorneys.

Only 13 of more than 2,000 Mexicans subject to the policy since it took effect got lawyers, and just 18 of more than 2,700 people from Guatemala, El Salvador and Honduras got representation, according to U.S. Sen. Kyrsten Sinema, an Arizona Democrat. The administration hasn't released figures on legal representation but hasn't disputed her numbers.

— The administration also has generally ruled out domestic and gang violence as grounds for asylum, allowed judges to decide cases without a hearing and denied asylum to people from countries with widespread communicable disease or who go through another country on their way to the U.S.-Mexico border.

Many of those trying to get to America use Tijuana, a Mexican city of about 2 million across from San Diego, as a jumping-off point. They take taxis or get rides to the outskirts of Tecate, a Mexican town of 100,000 with a namesake brewery.

Migrants pay $8,000 to $10,000 to be guided through the mountains and picked up by a driver once they reach a road, Border Patrol Agent Justin Castrejon said.

On a cool September evening, a voice over a Border Patrol radio said a suspicious vehicle was spotted on a two-lane highway near Tecate, California, which is little more than a gas station. Five people bailed out, with agents in pursuit, and hid in the brush before being caught. Around the same time, groups of seven and three people got picked up, along with a single man.

Migrants who are caught give fingerprints and have a photo taken, Scott said. They are held for charges only if they have serious criminal records in the U.S.

The Border Patrol began reporting recidivism rates annually to Congress in 2014 and uses them in performance reviews for top officials, said Michael Fisher, the agency's chief from 2010 to 2015. Agents flag routes attracting repeat crossers as weak spots.

“Recidivism rates told us how sick the patient was,” Fisher said. “If something wasn’t working, then we could drill down.”

It took two tries for Jose Luis Zarate to cross the border from Tijuana. Zarate, who recently finished nursing studies but couldn’t find a well-paid job, hopes to make enough money in Alabama to eventually build a basketball court in his hometown of Oaxaca, Mexico. He and his girlfriend decided it was too dangerous for her to follow with her 6-year-old son.

“It's frustrating, but I'm happy that I will begin to make money,” he said by text message. “I will begin a new life here, starting with nothing.”

Jose Edgar Zuleta, whose business selling religious jewelry in the Mexican city of Puebla dried up during the pandemic, climbed Trump's 30-foot (9-meter) wall with a special ladder. He moved through brush in a heavily patrolled area for about a half-hour with two women before getting caught. His 21-year-old son, who cleared the wall ahead of him, got picked up hours later.

Zuleta, 43, agreed to pay smugglers $19,000 for him and his son but only if they made it to the U.S., where they hope to work as landscapers in Southern California. He returned home to his wife and mother and plans to try again.

Without the threat of being jailed on criminal charges, Zuleta said the pandemic-related expulsions make it a good time to go to the U.S.

“It's a good thing for us because we can keep trying many times,” he said.