Meanwhile, some Democrats are questioning the basic legal underpinnings of U.S. immigration enforcement and challenging the long-held consensus that a robust detention and deportation system is necessary to prevent an even bigger wave of illegal border crossings into the United States.

On Tuesday, Sen. Cory Booker (D-N.J.) said he would “virtually eliminate immigration detention” by executive order. During last week’s debate, presidential candidate Julián Castro proposed decriminalizing illegal border crossings — a position other Democrats in the race rapidly adopted.

Others in the party are urging caution, saying the push toward decriminalization risks playing into Trump’s hands.

“That is tantamount to declaring publicly that we have open borders,” said Jeh Johnson, who ran the Department of Homeland Security during President Barack Obama’s second term. “That is unworkable, unwise and does not have the support of a majority of American people or the Congress, and if we had such a policy, instead of 100,000 apprehensions a month, it will be multiples of that.”