President Trump ordered the Department of Homeland Security on Friday to increase the deportation force of the United States by 20,000 officers, a move that would lead to an enormous expansion of immigration enforcement if realized.

In a provision tucked into a presidential proclamation focused on pushing undocumented immigrants to leave the country voluntarily, Mr. Trump called on the Department of Homeland Security to soon begin “deputizing and contracting with state and local law enforcement officers, former federal officers, officers and personnel within other federal agencies, and other individuals.”

It was unclear how such an effort would be funded, one of several major logistical hurdles to such a large operation. There are now around 6,000 officers focused on deportation efforts at Immigration and Custom Enforcement.

Mr. Trump has pushed to deputize state and local law enforcement officers for immigration enforcement before, and Department of Homeland Security officials have already signed a series of agreements with local law enforcement in the months since took office. Late last month, local law enforcement officials in Florida assisted ICE in an operation that led to the arrest of more than 1,100 migrants across the state.

The Trump administration has spent the past few months attempting to make good on the president’s promise of mass deportations by conducting sweeping raids in major cities, arresting international students and allowing officers more freedom where they make arrests, like in courthouses. But it has still struggled to reach the pace that would be necessary for Mr. Trump’s expansive deportation goals.

In recent weeks, the Trump administration has turned to pushing for migrants to leave the country on their own accord, a concept known as “self-deportation.” Earlier this week, department officials said they would pay migrants $1,000 and the cost of their travel if they left the country voluntarily and used a government app to do so.

In his proclamation Friday, Mr. Trump repeated that call, labeling it “project homecoming.”

“This proclamation establishes Project Homecoming, which will present illegal aliens with a choice: either leave the United States voluntarily, with the support and financial assistance of the federal government, or remain and face the consequences,” the proclamation read.

Mr. Trump ordered the Department of Homeland Security and the State Department to begin a “nationwide communications campaign” to tell migrants of the self-deportation offer and to warn them that not doing so would lead to stiffer consequences.

Beyond being arrested and deported, the proclamation warned that migrants could face “fines as consistent with applicable law for immigration-related crimes; the garnishment of wages; and the confiscation of savings and personal property, including homes and vehicles.”