Several hundred people marched through the streets of El Paso Saturday afternoon, and when they arrived at a group of migrants huddling outside a church, they sang to them “no estan solos” — “you are not alone.”

Around 300 migrants have taken refuge on sidewalks outside Sacred Heart Church, some of them afraid to seek more formal shelters, advocates say, amid new restrictions meant to crack down on illegal border crossings.

This is the scene that will greet President Joe Biden on his first, politically thorny visit to the southern border Sunday.

The president announced last week that Cubans, Nicaraguans, Haitians and Venezuelans will be expelled to Mexico if they enter the U.S. illegally — an expansion of a pandemic-era immigration policy called Title 42. The new rules will also include offering humanitarian parole for up to 30,000 people a month from those four countries if they apply online and find a financial sponsor.

Biden is scheduled to arrive in El Paso Sunday afternoon before traveling on to Mexico City to meet with North American leaders on Monday and Tuesday.

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Dylan Corbett, who runs the nonprofit Hope Border Institute, said the city is experiencing an increasing “climate of fear.”

He said immigration enforcement agencies have already started ratcheting up deportations to Mexico, and he senses a rising level of tension and confusion.

The president’s new policy expands on an existing effort to stop Venezuelans attempting to enter the U.S., which began in October.

Corbett said many Venezuelans have since been left in limbo, putting a strain on local resources. He said expanding those policies to other migrants will only worsen the circumstances for them on the ground.

“It’s a very difficult situation because they can’t go forward and they can’t go back,” he said. People who aren’t processed can’t leave El Paso because of U.S. law enforcement checkpoints; most have traveled thousands of miles from their homelands and refuse to give up and turn around.

“There will be people in need of protection who will be left behind,” Corbett said.

The new restrictions represent a major change to immigration rules that will stand even if the U.S. Supreme Court ends a Trump-era public health law that allows U.S. authorities to turn away asylum-seekers.

El Paso has swiftly become the busiest of the Border Patrol’s nine sectors along the U.S. border with Mexico, occupying the top slots in October and November. Large numbers of Venezuelans began showing up in September, drawn to the relative ease of crossing, robust shelter networks and bus service on both sides of the border, and a major airport to destinations across the United States.

Venezuelans ceased to be a major presence almost overnight after Mexico, under Title 42 authority, agreed on Oct. 12 to accept those who crossed the border illegally into the United States. Nicaraguans have since filled that void. Title 42 restrictions have been applied 2.5 million times to deny migrants a right to seek asylum under U.S. and international law on grounds of preventing the spread of COVID-19.

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U.S. authorities stopped migrants 53,247 times in November in the El Paso sector, which stretches across 264 miles of desert in West Texas and New Mexico but sees much of its activity in the city of El Paso and suburban Sunland Park, New Mexico. The most recent monthly tally for the sector was more than triple the same period of 2021, with Nicaraguans the top nationality by far, followed by Mexicans, Ecuadoreans, Guatemalans and Cubans.

Many gathered under blankets outside Sacred Heart Church. The church opens its doors at night to families and women, so not all of the hundreds caught in this limbo must sleep outside in the dropping temperatures. Two buses were available for people to warm up and charge their phones. Volunteers come with food and other supplies.

Juan Tovar held a Bible in his hands, his 7-year-old daughter hoisted onto his shoulders. The 32-year-old was a bus driver in Venezuela before he fled with his wife and two daughters because of the political and financial chaos that has consumed their home country.

He has friends in San Antonio prepared to take them in, he said. He’s here to work and provide an education for his daughters, but he’s stuck in El Paso without a permit.

“Everything is in the hands of God,” he said. “We are all humans and we want to stay.”

Another Venezuelan, 22-year-old Jeremy Mejia, overheard and said he had a message he’d like to send to the president.

“President Biden, I ask God to touch your heart so we can stay in this country,” Mejia said. “I ask you to please touch your heart and help us migrants have a better future in the U.S.”