Homeland Security Secretary Alejandro Mayorkas is again blaming root causes in Central America and elsewhere for the migrant surge at the southern border -- including a "pent up thirst for relief" from those making the journey north.

Mayorkas was asked by Yahoo News why he thinks that border crossings are at a 20-year-high, and again moved to the "root cause" explanation favored by the administration -- as well as blaming the Trump administration for shutting down asylum pathways.

MAYORKAS ORDERS ICE TO STOP WORKSITE RAIDS IN LATEST LIMITS ON IMMIGRATION ENFORCEMENT

"I think that pieces of the many different theories compiled together form a very compelling answer," the secretary said. 

"The downturn in economies, the attendant rise in violence, the downturn in economies made more acute by reason of the impact of the COVID-19 pandemic, the suppression of any humanitarian relief over the past number of years, and the pent-up thirst for relief among many different populations," he said. "I think an accumulation of factors contributes to the rise in migration that we've seen."

There were more than 200,000 migrant encounters in both July and August, and the administration has also faced a Haitian migrant surge in September that saw more than 15,000 migrants camped out under the Del Rio International Bridge. Republicans have hammered the Biden administration for its policies, saying that its rolling back of Trump-era border protections are the reason for the surge.

BORDER CRISIS OVERWHELMING OFFICIALS, COMMUNITIES AS MIGRANT NUMBERS KEEP SURGING 
 

Mayorkas is reported to have warned that if Trump-era Title 42 public health protections -- which allow for the rapid expulsion of migrants due to the COVID-19 pandemic -- are ended, that the U.S. could see a new surge at the border.

The administration has been fighting in court to keep its limited application of Title 42 in place -- only 19% of migrant families were removed under the order in August.

CLICK HERE TO GET THE FOX NEWS APP

However, Mayorkas distanced himself from the policy, which has angered left-wing immigration activists, repeating a Trump-era claim that the Title 42 order is not an immigration authority but a public health authority.

"And the Title 42 authority is a public health authority. And it is not an immigration policy. It is not an immigration policy that we in this administration would embrace," he said. "But we view it as a public health imperative as the Centers for Disease Control has so ordered."