Former President Obama called for comprehensive immigration reform to fix a "dysfunctional" system as the Biden administration grapples with what he called a "heartbreaking" migrant crisis at the southern border. 

Obama, during an interview with ABC's "Good Morning America" that aired Tuesday, said reform to the U.S. immigration system is "something that is long overdue." He added that immigration is a "tough" issue because Americans want to be compassionate but that the U.S. having open borders is  an "unsustainable" idea.

Obama's comments come after more than 14,000 Haitian migrants camped under a bridge in Del Rio, Texas, after a surge in border crossings. 

Secretary of Homeland Security Alejandro Mayorkas admitted Sunday that the vast majority of Haitian migrants who crossed the southern U.S. border in recent weeks have already been released into the United States and it is possible that more will follow them.

So far, approximately 12,400 of the people are having their cases heard by immigration judges, while another 5,000 are being processed by the Department of Homeland Security. Only 3,000 are in detention.

Obama said the situation in Del Rio "is a painful reminder that we don't have this right yet and we've got more work to do." 

"As big-hearted as he is, nobody understands that better than Joe Biden," Obama said. "And the question is now: Are we gonna get serious about dealing with this problem in a systemic way, as opposed to these one-offs where we're constantly reacting to emergencies? And I think that that's something that every American should wanna put an end to."

Obama added that "immigration is tough" and "always has been."

"Immigration is tough. It always has been because, on the one hand, I think we are naturally a people that wants to help others," Obama said. "And we see tragedy and hardship and families that are desperately trying to get here so that their kids are safe, and they're in some cases fleeing violence or catastrophe."

He added: "At the same time, we're a nation state. We have borders. The idea that we can just have open borders is something that ... as a practical matter, is unsustainable."