Should President Trump follow through on a deal where nearly 800,000 illegal aliens are allowed to remain in the United States and eventually obtain U.S. citizenship, research shows it would create a flood of four to six million chain migrants coming to the United States.

Trump, who adamantly opposed the amnesty for illegal aliens protected by the Deferred Action for Childhood Arrivals (DACA) program, is now defending the recipients of the program, as well as leveraging a deal where the foreign nationals could seek a pathway to citizenship through legal status, as Breitbart News reported.

Today, Trump signaled to his supporters that he opposed any sort of chain migration that would follow a DACA amnesty deal, though the deals the White House and Congress are reviewing would all cause such an immigration crisis:

CHAIN MIGRATION cannot be allowed to be part of any legislation on Immigration! — Donald J. Trump (@realDonaldTrump) September 15, 2017

Latest data from the United States Citizenship and Immigration Services (USCIS) shows that 618,342 illegal aliens from Mexico currently have DACA status. If they were amnestied into the U.S., it would give them the opportunity to bring adult parents and relatives to the U.S.

“There will be chain migration. There always has been in amnesties,” Center for Immigration Studies Policy Director Jessica Vaughan told Breitbart News.

According to Princeton University researchers Stacie Carr and Marta Tienda, for every one new Mexican immigrant to the U.S., an additional 6.38 Mexican nationals come to the U.S. through family-chain migration.

Based on the Princeton research, the 618, 342 illegal aliens from Mexico who are covered by DACA would be able to bring upwards of four million additional relatives and family members to the U.S. in the years to come.

If the remaining estimated 180,000 DACA recipients brought in three family members each after being amnestied, it would result in additional 540,000 immigrants. Should the remaining 180,000 DACA recipients bring four family members each to the U.S., it would result in more than 700,000 new immigrants.

But if the remaining roughly 180,000 DACA recipients were to bring the same number of family members as Mexican DACA recipients are expected to bring to the U.S., it would result in nearly 1.2 million more legal family-based immigrants coming to the country.

On top of the legal chain migration that could occur following a DACA amnesty by Trump, there is also the potential for a massive border surge, like the one that occurred following former President Obama’s creation of the DACA program.

As the Migration Policy Institute has chronicled, previous border surges from amnesty programs have brought hundreds of thousands across the U.S.-Mexico border:

While the flow of Unaccompanied Alien Children (UACs) has been climbing steadily since 2012, a dramatic surge has taken place in the last six months, with the Rio Grande Valley in South Texas as the principal place of entry. The Border Patrol there has converted entire stations to house unaccompanied minors and families. According to the Border Patrol, apprehensions of unaccompanied children increased from 16,067 in fiscal year (FY) 2011 to 24,481 in FY 2012 and 38,833 in FY 2013. During the first eight months of FY 2014, 47,017 such children were apprehended by the Border Patrol. If the influx continues apace—and it shows no signs of slowing—the administration predicts that by the end of the fiscal year on September 30, totals could reach 90,000. Ninety-eight percent of unaccompanied minors currently arriving at the border are from Honduras (28 percent), Mexico (25 percent), Guatemala (24 percent), and El Salvador (21 percent). This breakdown represents a significant shift: prior to 2012, more than 75 percent of UACs were from Mexico.

“There’s one thing for sure: it’s not going to be 800,000 illegal aliens amnestied,” Vaughan said, alluding to the fact that an amnesty would surge both legal and illegal immigration.