"The border is just as tough," he said as he signed the executive order.

Liberal advocacy group Southern Poverty Law Center said Trump's order to reverse the policy of family separations doesn't go far enough.

In a statement, the president of the organization, Richard Cohen, said indiscriminate enforcement is "shattering" communities across the country.

Trump also said Wednesday that he will "be doing something that's somewhat preemptive but ultimately will be matched by legislation," as lawmakers are struggling to find common ground on legislative solutions to family separations.

The president met House Republicans on Tuesday discuss immigration legislation, with the family separation policy as a central topic.

In a surprise move, Trump suggested that he would postpone a picnic for US lawmakers and their families at the White House scheduled for Thursday while they sort out the immigration issue.

"We want to see if we can solve it, so we're cancelling or postponing the congressional picnic tomorrow," Trump said.

House Speaker Paul Ryan said Wednesday that the chamber will vote on immigration legislation on Thursday that would end family separations, but the chances of its passing are unclear.