U.S. authorities at the southern border stopped more than 100,000 unauthorized crossing attempts from Mexico last month, according to figures released by Customs and Border Protection on Wednesday.

The continued increase in arrests marks the highest monthly total since Border Patrol stations were overwhelmed by an influx of migrant families in the Spring of 2019. Roughly a quarter of those crossing are repeat offenders, one senior CBP official told reporters. But resources at the border remain strained.

Biden administration officials have pointed to former President Donald Trump‘s hardline measures and heavy focus on border wall construction as having detracted from the more urgent objective of setting up processing centers and building capacity to handle migrants amid the pandemic.

The president’s critics and immigration hardliners have blamed the easing of restrictions at the border which they say have signaled migrants to make the dangerous journey through Mexico.

“We’ve dealt with these types of numbers before but what we haven’t dealt with are the day-to-day increases that we’re currently seeing,” said Brandon Judd, president of the National Border Patrol Council. “It’s strictly based on the promise that people are going to be allowed into the United States again.”

White House press secretary Jen Psaki said Wednesday that the president was briefed by administration officials who visited a tent facility housing migrant children in Carrizo Springs, Texas, over the weekend. The delegation included Homeland Security Secretary Alejandro Mayorkas and domestic policy adviser Susan Rice, but Psaki did not specify who briefed Biden.

“They spent the majority of their time discussing what steps can be taken to expedite processes to move more quickly — to move the process more quickly to meet the administration’s goal of getting these children placed with vetted and confirmed families,” Psaki said.

Though many expect an infrastructure bill to be the White House’s next major legislative push, Psaki Wednesday suggested immigration reform could be addressed sooner rather than later, given all the attention on the growing crisis.

A group of Republican lawmakers will travel to the border next week led by House Minority Leader Kevin McCarthy. He sent a letter to the White House earlier this month in which he noted the elevated number of crossing attempts and his concern over the administration’s handling of it.

“I feel compelled to express great concern with the manner in which your administration is approaching this crisis, but with hope that we can work together to solve it,” McCarthy wrote.

The number of unaccompanied minors in CBP custody has risen to just under 3,500 in recent weeks, according to sources and internal Customs and Border Protection documentation reviewed by ABC News.

The majority of kids in CBP custody are over the age of 13, while nearly 200 are under the age of 12, the documentation shows. Nearly 1,500 have been waiting longer than the legal limit of 72 hours without having been transferred to Health and Human Services.

When Border Patrol encounters minors traveling alone they are taken to stations for processing. These facilities are not typically equipped for long-term detention and federal law requires children to be transferred to Health and Human Services within 72 hours.

The number of monthly crossing attempts has not exceeded the largest monthly totals seen under the Trump administration, but compared to this time in previous years, the trend is significantly higher. Crossing attempts were more than three times as high last month compared to February and the numbers continue to rise.

Many adults are still getting turned back or “expelled” without the usual opportunity to make an asylum case. The policy is a hold-over from the Trump administration when it invoked a decades old public health law called “Title 42” to send people back within hours of their apprehension.

However, the Biden administration has eased back “Title 42” in some cases. It no longer applies to unaccompanied minors or some families with young children.

Also on Wednesday, the State Department announced it would resume the Central American Minors program which allows children to apply from their home countries to join family in the U.S. The program was abruptly ended by the Trump administration in 2017.

“Neither this announcement nor any of the other measures suggest that anyone, especially children and families with young children, should make the dangerous trip to try to enter the U.S. in an irregular fashion,” said Roberta Jacobson, White House policy coordinator for the southwest border. “The border is not open.”

The question of whether the Biden team relaxed Trump-era hardline measures too soon continues to confront administration officials who so far point to the need to fully rebuild the immigration system with a more humane approach.

“There is one government at a time,” Jacobson said. “You can’t start changing processes of government building facilities. All of this is part of the plan, as quickly as possible, to make sure that our domestic processing is working more smoothly, more quickly … and you can’t do that, obviously, until Jan. 20 when you take over.”

However, Jacobson acknowledged Wednesday that the appearance of a more humane policy may prompt some to attempt crossing despite similar migration patterns in the past.

“Surges tend to respond to hope,” Jacobson said. “And there was a significant hope for a more humane policy after four years of pent up demand.”

ABC News’ ABC News Chief National Correspondent Matt Gutman, Benjamin Siegel, Katherine Faulders, Sarah Kolinovsky and Mariam Khan contributed to this report.