"I believe the time has come for new immigration rules which say those seeking admission into our country must be able to support themselves financially and should not use welfare for a period of at least five years," Trump said to raucous applause from the roughly 6,000 supporters who flocked to his Iowa rally.
With a few exceptions, new immigrants already cannot access welfare programs during their first five years in the US, per a 1996 welfare reform law signed by President Bill Clinton.
Pressed repeatedly by CNN, a senior administration official did not dispute that the proposal is already in effect.
The official said that Trump is aiming for a "total rewrite of our immigration system" that would produce a "merit-based system for entry."
The official pointed to Trump's comment Wednesday night that "those seeking admission into our country must be able to support themselves financially," but declined to offer additional details about that proposal.
"There are many welfare benefits for which immigrants would no longer be eligible," the senior administration official said.
Several categories of legal immigrants are exempt from the five-year ban on accessing government welfare programs, including children, refugees and veterans of the US military.
But neither Trump nor the senior administration official who discussed the proposals with CNN said Trump was calling for legislation to scrap those exemptions to the 1996 law, which was negotiated in large part by then-House Speaker Newt Gingrich, a Republican, and Clinton, a Democrat.
Reached for comment, a White House spokesman would only say that Trump addressed his vision for a merit-based immigration system in his joint address to Congress and in his 2018 budget proposal, though neither address changes to the 5-year welfare ban.
The spokesman said Trump wants a "merit-based system for entry that requires self sufficiency."
"Not new," the spokesman said.