WASHINGTON (BLOOMBERG) - President Joe Biden is struggling to head off a potential humanitarian and political crisis on the United States' southern border, where a spike in migrant crossings - particularly by unaccompanied children - threatens to overwhelm government shelters.

White House officials briefed Mr Biden earlier this week on the surge, and the administration has held multiple briefings with House and Senate lawmakers on the situation, according to congressional aides.

Homeland Security officials are giving weekly updates to several Capitol Hill offices.

"We'll be able to handle it, God willing," Mr Biden said on Tuesday (March 2). But when asked whether the surge constituted a crisis, the President was clear: "No."

The administration has taken steps to clear shelter space by speeding the release of unaccompanied minors to relatives or sponsors in the US, and Homeland Security Secretary Alejandro Mayorkas said additional measures are on the table.

But the situation could worsen if the flow of migrants continues to rise.

More than 5,700 unaccompanied minors were apprehended at the border in January, the highest total for that month in recent years, according to the Department of Homeland Security.

At the end of the month, about 5,100 children and teenagers were in the custody of the Department of Health and Human Services' (HHS) Office of Refugee Resettlement (ORR), which runs the shelters.

By late February, the number of minors in custody had risen to 7,000, a sign that the influx is not abating. About 90 per cent of shelter capacity was occupied, stretched not only by the influx of migrants but also by space restrictions due to the Covid-19 pandemic, according to a congressional aide familiar with the administration's briefings.

To assist the refugee office, HHS awarded a US$3.34 million (S$4.45 million) sole-source contract for child advocates to help deliver care that is required by law, according to Bloomberg Government contracting data.

HHS cited a "significant increase in referrals" to the Unaccompanied Alien Children programme and "unpredictability in influx numbers" to justify the six-month, non-competitive contract that went into effect last Friday.

The situation poses a challenge for Mr Biden, whose promise to implement a more humane immigration system has given way to an acknowledgement that it could take more time due to the health and economic problems facing the US.

The President is also facing criticism from Republicans and a handful of Democrats that his policies are to blame for the influx and that he is downplaying a national crisis.

"Do we have a crisis? No. Are we getting there? At this rate, yes we are," Representative Henry Cuellar, a Texas Democrat, said in an interview.

Mr Biden's decision to stop expelling children who arrive alone at the border - as former president Donald Trump's administration did after the pandemic began - means that the government needs more space in permanent shelters to house them.

The situation has prompted the Biden administration to reopen a Trump-era temporary facility for child migrants in Carrizo Springs, Texas, that prompted protests from immigrant-rights advocates.

"It's clear that they're already facing significant problems because nobody wants to open an influx facility, but they've had to," said Mr Mark Greenberg, a senior fellow at the Migration Policy Institute who led HHS' Administration for Children and Families, which oversees ORR, under president Barack Obama.

"So there's no question that they will be facing continuing challenges in how to manage arrivals, even at the current level." The administration is confronting the problem without key officials in place at two central agencies: US Immigration and Customs Enforcement and Customs and Border Protections.

Mr Biden's nominee for HHS secretary, Mr Xavier Becerra, still has not won Senate confirmation, though Ms Cindy Huang was recently installed as the new director of ORR.

Republicans have blamed the situation at the border on Mr Biden, saying that his efforts to reverse Mr Trump's hard-line immigration policies and introduction of a Bill that would offer a path to citizenship to 11 million undocumented immigrants have encouraged migrants from Central America to make the journey north.

"If this isn't a crisis, with unaccompanied kids pouring in and exceeding capacity amid a pandemic, then I'd sure hate to see one," Senate Minority Leader Mitch McConnell said in a floor speech on Wednesday.

"The cause of this emergency is not some mystery. Everyone knows what's happened."

White House officials have repeatedly said now is not the time to migrate to the US and that migrants are driven north by conditions in Central America, not Mr Biden's policies.

A Homeland Security official said that overall border encounters have been rising since April 2020, eight months before Mr Biden took office. Violence and natural disasters in the Northern Triangle countries - Guatemala, Honduras and El Salvador - have driven the increase, according to the official.

Mr Biden has not yet implemented many of his proposed immigration policy changes. The vast majority of migrants arriving at the US-Mexico border are turned away.

Congress has not passed his immigration overhaul that includes a citizenship path, which many Republicans have derided as an inappropriate "amnesty" for unauthorised immigrants.

Yet some Democrats representing areas along the border have said Mr Biden's aggressive push to unwind Mr Trump's policies is nonetheless causing confusion and could lead migrants to believe they will be allowed into the US.

They cite the administration's welcoming rhetoric and measures such as speeding entry for certain asylum seekers who have waited for months in Mexico under the Trump administration.

Representative Vicente Gonzalez, a Texas Democrat, urged Mr Biden to change course, warning that his party could find itself in a political bind if tens of thousands of migrants show up at the border.

'Catastrophic for our party'

"It will be catastrophic for our party, for our country, for my region and for my district in the middle of a pandemic," Mr Gonzalez said this week on CNN. "So, I think we need to have a better plan in place."

Mr Cuellar said that migrants have the impression Mr Biden is "letting undocumented people come into the United States and you're not letting those legal visa holders come in" due to pandemic-related border restriction.

There is a danger that human smugglers could use Mr Biden's policy and messaging shift to persuade migrants to travel to the US, he added.

"Even though the Mr Biden administration is saying 'don't come,' the bad guys, they're on a different wavelength," he said.

Mr Obama faced a political crisis in 2014, when the first major exodus of unaccompanied children from Central America caused the administration to build an influx centre with chain-link fencing inside an Arizona warehouse. Images of children behind the fences shocked the nation.

Mr Biden's decision to reopen the Carrizo Springs camp angered liberals, who said migrant children live there in poor conditions.

"This is not okay, never has been okay, never will be okay - no matter the administration or party," Representative Alexandria Ocasio-Cortez said on Twitter.

White House officials said the facilities has been revamped to include teachers and expanded medical services.

"Well, it's much different in terms of more people there helping them," Mr Biden said in an interview with Univision last Friday.

"We have people that are in those facilities taking care of them. But my hope is they all are able to get out, all are able to get into licensed facilities and/or be united with family members here in the United States."

Immigration policy experts say that it is no guarantee the number of unaccompanied minors crossing into the US will stay on its current trajectory and reach record highs. The number of children who cross the border alone typically increases in the spring, then recedes, according to Homeland Security data.

A Customs and Border Patrol official said the number of individuals crossing the border continues to fluctuate and the agency will adapt accordingly.