SAN DIEGO (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.

A rescue helicopter couldn’t land in the steep terrain but authorities dropped water before border agents arrived and whisked him back to Tijuana, Mexico. Lopez quickly recovered and began planning his another attempt to reach San Diego, where he hoped to settle to earn a more steady living.

“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's 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 to Mexico 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's crossing the border illegally: more Mexican men coming 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 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 a recent two-week period in the Border Patrol’s San Diego sector, said Chief Rodney Scott.

“They can get a night’s rest and try again,” he 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.

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,” Scott said.

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.

“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.

Critics say the pandemic-inspired halt to asylum, which is being challenged in court, is a gross abdication of legal and moral obligations to protect people fleeing human rights abuses.

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 have been returned to Mexico since January 2019 to wait for court hearings. It’s subjected them to violence and made it even more difficult to find attorneys. Less than 1% have won claims, far below rates for all seeking asylum.

Democrat Joe Biden has pledged to end the policy.

— The administration struck agreements with Guatemala, El Salvador and Honduras last year for asylum-seekers 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.

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.

Many of those trying to get to America use Tijuana, across the border from San Diego, as a jumping-off point.

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.

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 but soon got caught.

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 plans to try again while the pandemic-related expulsions are in place.

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