WASHINGTON — President Joe Biden plans to lift his predecessor’s historically low cap on refugees by next month, after initially moving only to expand the eligibility criteria for resettlements and getting swift blowback from allies in return.

In an emergency determination signed Friday, Biden stated the admission of up to 15,000 refugees set by President Donald Trump this year “remains justified by humanitarian concerns and is otherwise in the national interest.” But if the cap is reached before the end of the current budget year and the emergency refugee situation persists, then a presidential determination may be issued to raise the ceiling.

That set off a deluge of criticism from top allies on Capitol Hill such as the second-ranking Senate Democrat, Dick Durbin of Illinois, who called that initial limit “unacceptable.”

White House press secretary Jen Psaki said later that Biden is expected to increase the refugee cap by May 15, though she didn’t say by how much.

Asked Saturday by reporters about the cap, Biden didn’t offer new details. “We’re going to increase the number,” he said after golfing in Wilmington, Delaware. “The problem was that the refugee part was working on the crisis that ended up on the border with young people. We couldn’t do two things at once. But now we are going to increase the number.”

Biden has been consulting with his advisers to determine what number of refugees could realistically be admitted to the United States between now and Oct. 1, the end of the fiscal year, Psaki said. “Given the decimated refugee admissions program we inherited,” she said it’s now “unlikely” Biden will be able to boost that number to 62,500, as he had proposed in his plan to Congress two months ago.

But Biden, she said, was urged by advisers to “take immediate action to reverse the Trump policy that banned refugees from many key regions, to enable flights from those regions to begin within days; today’s order did that.”

The new allocations provide more slots for refugees from Africa, the Middle East and Central America and lift Trump’s restrictions on resettlements from Somalia, Syria and Yemen.

Critics from both sides of the political spectrum had accused the president of bowing to political pressure that has been mounting over the record pace of unaccompanied migrants crossing the U.S.-Mexico border. Stephen Miller, a key architect of Trump’s immigration policies, tweeted that keeping Trump’s cap “reflects Team Biden’s awareness that the border flood will cause record midterm losses.”

The White House indicated the border situation was partly why Biden had not acted before now, even though migrants at the border do not go through the same vetting process as refugees.

“It is a factor,” said Psaki, noting that the Office of Refugee Resettlement “has personnel working on both issues and so we have to ensure that there is capacity and ability to manage both.”