US President Joe Biden announces an executive order on enforcement at the US-Mexico border, as he remarks in the East Room of the White House in Washington, on June.4. / Reuters/Leah Millis

WASHINGTON (Reuters) - US President Joe Biden on June.4 instituted a broad asylum ban on migrants caught illegally crossing the US-Mexico border, a major enforcement move in the run-up to November elections that will decide control of the White House.

Migrants caught crossing illegally could be quickly deported or turned back to Mexico under the measure, which will take effect just after midnight. There will be exceptions for unaccompanied children, people who face serious medical or safety threats and victims of trafficking, the US Department of Homeland Security said.

Biden, a Democrat, has toughened his approach to border security as immigration has emerged as a top issue for Americans in the run-up to Nov.5 elections where he will face Republican Donald Trump, who made a hardline stance on immigration a centerpiece of his administration and vowed a wide-ranging crackdown if reelected.

Biden took office in 2021 vowing to reverse some of Trump's restrictive immigration policies but grappled with record levels of migrants caught crossing illegally, a trend that has strained US border authorities and cities receiving new arrivals.

During a White House press conference explaining the proclamation, Biden said asylum access would remain available to migrants who registered for an appointment using an app known as CBP One or used other legal pathways instead of crossing illegally.

"This action will help us gain control of our border and restore order into the process," Biden said. "This ban will remain in place until the number of people trying to enter illegally is reduced to a level that our system can effectively manage."

Even as Biden rolled out new restrictions, he criticized Trump's most controversial policies, including separating migrant families at the border and comments that immigrants in the US illegally were "poisoning the blood of our country."

"I will never demonize immigrants," Biden said.

When it comes to immigration policy, registered voters prefer Trump over Biden by a 17 percentage point margin, according to a Reuters/Ipsos poll conducted in mid-May.

QUESTIONS REMAIN

The new asylum ban becomes active when the daily average of border arrests tops 2,500 over a week, and figures are currently higher than that, officials said on a call with reporters, requesting anonymity as a condition of the call.

US border arrests averaged 4,300 per day in April, according to the most recent government statistics available.

The ban will be paused when arrests drop below an average of 1,500 per day for three weeks. The last time crossings fell to that level was in the early months of the Covid-19 pandemic in July 2020 when global travel was at historic lows.

Key operational questions about the measure's implementation remained unclear, including how the administration would quickly deport migrants from far-away and uncooperative countries and how many non-Mexican migrants Mexico would accept under the new enforcement regime.

The new restrictions resemble similar policies implemented by Trump and use a legal statute known as 212(f) that served as the underpinning for Trump's travel bans blocking people from several majority-Muslim nations and other countries.

The Biden ban was attacked by critics on both sides of the political spectrum on June.4.

Lee Gelernt, an attorney for the American Civil Liberties Union, said they intended to sue over the new restrictions. The group and other immigrant advocacy organizations have criticized Biden for adopting Trump-like policies and backtracking on U.S. legal obligations to asylum seekers.

In advance of the announcement, Trump's campaign issued a statement criticizing Biden for high levels of illegal immigration and said the move to exempt unaccompanied minors would encourage child trafficking.

Republicans also slammed Biden's moves as politically motivated and insufficient.

INACTION IN CONGRESS

Biden has pushed unsuccessfully for months to pass a Senate bill crafted by a bipartisan group that would toughen border security but Republicans rejected it after Trump came out in opposition.

In addition to the latest measure, the Biden administration has taken a number of steps over the past year to toughen the asylum process, including issuing a regulation in May 2023 that heightened the standard for an initial asylum claim.

The number of migrants caught crossing the US-Mexico border illegally dropped in recent months, a trend US officials partly attribute to increased Mexican enforcement.

Claudia Sheinbaum was elected as Mexico's first female president in a landslide victory on June.2 and will take office on Oct.1. Biden's border restrictions could put pressure on Sheinbaum, the successor to current President Andres Manuel Lopez Obrador, to keep illegal border crossings down.

Biden thanked Lopez Obrador on a phone call on June.4 for his continued cooperation on immigration and Lopez Obrador at his daily press conference said the two countries "have been making good progress" on the issue.

Enrique Lucero, the director of migrant affairs in Tijuana, Mexico warned the new measures could overwhelm migrant shelters as more people will be stuck waiting or returned. He said he thought desperate people would continue to find ways to cross the border illegally.

"The question is where are all those people going to go?" Lucero said. "Many will end up on the streets or prey to traffickers."

Across the border from Tijuana in San Diego, California, a 31-year-old Colombian man who identified himself as John said he spent eight days and 20 million Colombian pesos ($5,200) to cross into the US and seek asylum. He said his immigration court hearing is scheduled for Apr.25.

"It would have been very painful to have to start over, in debt," John said. "People give up everything they have."