GOOD EXAMPLE FOR YOUR KIDS. >>> IT'S SO GREAT TO HAVE YOU WITH US. WELCOME TO NBC NEWS DAILY. A NEW PUSH FROM THE WHITE HOUSE TO CRACK DOWN ON THE NUMBER OF MIGRANTS CROSSING THE SOUTHERN BORDER. IN JUST A FEW HOURS, PRESIDENT BIDEN IS EXPECTED TO SIGN AN EXECUTIVE ORDER THAT COULD TEMPORARILY SHUT DOWN THE BORDER TO MANY ASYLUM SEEKERS. >> ACCORDING TO SOURCES FAMILIAR WITH THAT PLAN, IT WOULD HAPPEN ONCE THE NUMBER OF DAILY ILLEGAL CROSSINGS HITS 2,500. THE BORDER WOULDN'T REOPEN UNTIL IT DROPS TO 1,500. HOMELAND SECURITY OFFICIALS SAY THEY'RE SEEING AN AVERAGE MORE THAN 4,000 ENCOUNTERS EACH DAY. ONCE MR. BIDEN SIGNS OFF, THE POLICY COULD TAKE EFFECT IMMEDIATELY. DAVID, A LOT OF PEOPLE HAVE BEEN SPEAKING OUT ABOUT THIS AND REALLY WHAT THE IMPLICATIONS MEAN DAY-TO-DAY. I KNOW YOU'VE BEEN SPEAKING WITH MIGRANTS DIRECTLY THERE TODAY. GIVE US A SENSE OF THE SITUATION ON THE GROUND RIGHT NOW. DO THEY FEEL A SENSE OF PANIC? >> Reporter: SO THE BIG QUESTION RIGHT NOW IS WHETHER WE'RE ACTUALLY GOING TO SEE THIS IMPLEMENTED AT ALL. IT IS ALMOST CERTAINLY GOING TO BE CHALLENGED IN COURT AND WE CAN TALK ABOUT THAT. BUT IN THE MEANTIME, WHAT I'VE BEEN DOING IS TALKING TO MIGRANTS HERE AT THE BORDER AND GETTING A SENSE OF WHETHER THEY'RE AWARE THAT THIS IS EVEN HAPPENING. GENERALLY, THE ANSWER IS NO. THAT TRACKS WITH WHAT I'VE LEARNED OVER THE YEARS OF REPORTING ON THE BORDER, IT'S RARE FOR MIGRANTS TO BE AWARE IN ANY SPECIFIC, MEANINGFUL WAY OF CHANGES TO U.S. POLICY. THEY'RE VERY IMPORTANT MEDIARIES AND CARTELS THAT ARE BECOMING INCREASINGLY ENGAGED IN THE SMUGGLING BUSINESS ACCORDING TO U.S. LAW ENFORCEMENT OFFICIALS. I HEARD FROM SEVERAL MIGRANTS TODAY A LOT OF THEM WERE WAITING ON THE OTHER SIDE OF THAT FENCE FOR DAYS OR SOMETIMES EVEN WEEKS AND THEN WERE TOLD THEY HAD TO CROSS THIS MORNING. SOME ADVOCATES WHO PROVIDE HUMANITARIAN AID TO MIGRANTS ON THE GROUND SAW THEY SAW A SUBSTANTIAL SPIKE IN CROSSINGS YESTERDAY. THAT COULD REPRESENT SMUGGLERS PUSHING PEOPLE BEFORE THIS GOES INTO EFFECT. IT'S HARD TO KNOW. I THINK IF THIS DOES, IN FACT, GO INTO EFFECT, IT WILL CATCH A LOT OF MIGRANTS BY SURPRISE. THERE'S PROBABLY GOING TO BE A LOT OF KIND OF UNCERTAINTY AND CHAOS HERE ON THE GROUND AT LEAST IN THE FIRST FEW DAYS WHILE WE FIGURE OUT WHAT THIS ACTUALLY LOOKS LIKE IN PRACTICE. >> THAT MAKES SENSE, DAVID. ADVOCACY GROUPS ARE SIGNALING THEIR PLANS TO CHALLENGE THIS ORDER IN COURT IF IT GOES THROUGH. IF IT DOES HAPPEN, WHAT COULD THAT MEAN FOR THE POLICY? ARE WE JUST GOING TO SEE IT HUNG UP IN COURT FOR MONTHS? >> Reporter: THAT IS REALLY THE MILLION DOLLAR QUESTION. THIS IS FOR SURE GOING TO BE CHALLENGED IN COURT. I ACTUALLY SAT DOWN WITH HOMELAND SECURITY SECRETARY MAYORKAS. HE EXPECTS ANY KIND OF EXECUTIVE ACTION LIKE THIS TO BE CHALLENGED IN COURT. THE QUESTION IS WHETHER THE COURTS AND THE VARIOUS LEVELS OF APPELLATE COURTS WILL ALLOW THE POLICY TO BE IMPLEMENTED WHILE THE LEGAL CHALLENGES RUN THEIR WAY THROUGH THE LEGAL SYSTEM OR NOT. THAT IS A QUESTION THAT WE DON'T KNOW THE ANSWER TO, AND WE'RE NOT GOING TO KNOW THE ANSWER TO UNTIL THE LEGAL CHALLENGES ACTUALLY BEGIN. FOR ME HERE ON THE GROUND, THAT IS REALLY, REALLY THE BIG QUESTION. WILL THIS ACTUALLY GO INTO EFFECT OR NOT? WILL THE COURTS ALLOW IT TO GO INTO EFFECT EVEN IF IT'S TEMPORARILY? WE'LL LIKELY SEE BIG MATERIAL CHANGES IN TERMS OF WHAT PEOPLE ACTUALLY EXPERIENCE ONCE THEY STEP ON U.S. SOIL, YOU KNOW, IN PLACES LIKE HERE IN SAN DIEGO. >> A