Can Biden 'shut down' the border right now?

President Biden is adopting newly hawkish rhetoric on migration, pledging twice over the weekend to "shut down" the border if given the power by bipartisan Senate legislation that is still under negotiation.

That claim drew fire from both the left and right. Immigration advocates were shocked at Biden's pivot, and Republicans said Biden doesn't need the Senate bill to shut down the border.

He is far from the first president to use hawkish border policy as a cudgel, but no U.S. commander in chief has successfully ended all border traffic — though some have created chaos by trying.

Given the context of Biden's statement, it's also clear his "shutdown" would be limited in scope to asylum-seekers rather than an interruption of regular traffic and commercial crossings.

Under current U.S. asylum law, any foreign national present on U.S. soil is afforded the right to claim asylum, in principle dispelling any claim that the federal government can currently limit asylum.

Yet both the Biden and Trump administrations put severe restrictions on asylum through Trump-initiated programs including Title 42 and the Migrant Protection Protocols, better known as "remain in Mexico."

Trump-era border policies largely focused on the idea of bouncing migrants back to Mexico or their home countries, either by summarily expelling them or by initiating their asylum claims but forcing applicants to wait out resolution of their cases outside of U.S. territory.

According to reports, the Senate border negotiations underway — endorsed by Biden and both Democratic and Republican Senate leadership — would set a cap on how many asylum claims federal officials would initiate daily at the border, potentially expelling any asylum-seekers over that cap.

Biden's claim that he needs the Senate deal to implement either that cap or a complete cessation of initial asylum processing drew fire from Speaker Mike Johnson (R-La.), an opponent of the Senate deal.

“President Biden falsely claimed yesterday he needs Congress to pass a new law to allow him to close the southern border, but he knows that is untrue," Johnson wrote in a statement Saturday.

“As I explained to him in a letter late last year, and have specifically reiterated to him on multiple occasions since, he can and must take executive action immediately to reverse the catastrophe he has created."

Johnson spokesperson Raj Shah said Monday on social media that "the new legal authority the President is seeking shouldn’t wait for 4,000 to 5,000 daily illegal crossings."

White House spokesperson Andrew Bates fired back Tuesday.

"Both cannot be true. Presidents either currently have the legal authority necessary to secure the border … OR presidents need additional legal authority to secure the border," Bates said in a statement.

"Either Speaker Johnson’s interpretation of the law radically changed over the last 4 days, or Speaker Johnson is twisting himself into a pretzel to delay border security — including urgently — needed Border Patrol hiring and investments in cutting-edge fentanyl detection technologies.”

The different interpretations reflect the often contradictory or unrealistic nature of immigration statutes, a hodgepodge of legislation often passed under deadline or trying political conditions.

Johnson, for instance, said the "Immigration and Nationality Act coupled with recent Supreme Court precedent give [Biden] ‘ample authority’ to ‘suspend the entry of all aliens or any class of aliens as immigrants or nonimmigrants, or impose on the entry of aliens any restrictions he may deem to be appropriate.’"

That law is generally understood to mean border officials can turn away people seeking entry into the United States at ports of entry, rather than an umbrella authority for Border Patrol to forcefully prevent foreign nationals from setting foot on U.S. soil.

The latter interpretation is further complicated by geographical realities at the border, where in many cases border barriers are wholly within U.S. territory, sometimes hundreds of yards from the actual border, meaning people on either side of the barriers are technically in the United States.

Because Trump-era summary expulsion or remain in Mexico programs either expired or were ended by the Biden administration, there's little legal precedent to conclusively state whether such programs are constitutional or compatible with asylum law.

Title 42, which relied on summary expulsions, was in litigation before it expired, and the Supreme Court rendered moot its review of the policy.

Yet a Senate deal could in theory give Biden statutory authorities, which would be inherited onward to his successor, to implement an expulsion policy much better bulletproofed against lawsuits.

Immigration advocates say that would be a step backward.

"It would be deeply misguided to revive an expulsion policy that contributed to more disorder and repeat crossings at the southern border,” said Krish O’Mara Vignarajah, president and CEO of Global Refuge.

“Policy makers should instead focus on managing migration humanely and efficiently in order to align our immigration system with our humanitarian values and economic needs. Meaningful solutions to this challenge lie in stronger federal coordination, expedited access to work permits, and robust investments in processing capacity, immigration courts, and community-based support programs."

And any policy involving returns or expulsions to Mexico of third-country nationals would require Mexico's acquiescence.

Trump obtained that cooperation threatening tariffs across the board; Biden has not issued bald threats and has maintained migration talks with Mexico led by Secretary of State Antony Blinken and Secretary of Homeland Security Alejandro Mayorkas, who is currently facing GOP impeachment articles centered on the administration's handling of the border.

Shortly before the first round of those talks in December, Customs and Border Protection (CBP) officials shut down regular traffic at a handful of legal ports of entry, arguing that CBP officials needed to assist the Border Patrol in dealing with prospective asylum-seekers between ports of entry.

Those ports were reopened shortly after the first round of meetings between Biden officials and Mexican President Andrés Manuel López Obrador, coinciding both with elevated Mexican immigration enforcement and a seasonal lull in border crossings after a record-setting December.