Sessions made his comments in an appearance
on ABC's "This Week," where he was attempting to square Trump's promise that Mexico would pay for the border wall with Mexico's firm position to the contrary.
"We're going to get it paid for one way or the other," Sessions said.
Trump took to Twitter on Sunday morning to say the wall would stop drugs and the gang MS-13. He also said that Mexico would pay for the wall "in some form."
Trump promised during the campaign that within his first 100 days as president he would get Congress to pass legislation fully funding the wall and establishing mandatory minimum prison sentences for people illegally entering the US after already being deported. That promise, one of many in his "Contract with the American Voter
," said Mexico would reimburse the US for the cost of the wall.
Trump has also threatened to target remittances
, or cash transfers from people within the US to people in Mexico.
Sessions referenced a Treasury Department watchdog report during the Obama administration that said excess payments of about $4 billion a year were going to people that shouldn't get them, and he said reining in the problem could lead to savings over time that could pay for the wall.
"These are mostly Mexicans," Sessions said. "And those kind of things add up. Four billion a year for 10 years is 40 billion."
The Treasury Inspector General for Tax Administration issued a report in 2011 saying people who were not authorized to work in the US were paid $4.2 billion in refundable tax credits in one year.
The Justice Department did not respond Sunday to a question asking if the report is the one Sessions referenced. The Treasury inspector general also did not return a request for information on whether any actions were taken following the release of the report and if more up-to-date figures exist.
An internal estimate
from Customs and Border Protection put the cost of the wall at $21.6 billion, while an estimate from Democrats on the Senate Homeland Security and Governmental Affairs Committee said the wall could cost as much as $66.9 billion.
Sessions implied other actions at the border and in trade could pay for the wall, although he said he did not expect the Mexican government itself to foot the bill.
"I don't expect the Mexican government to appropriate money for it," Sessions said. "But there are ways that we can deal with our trade situation to create the revenue to pay for it. No doubt about it."
The Trump administration has requested
a $1 billion "down payment" from Congress to begin construction of the wall. Administration officials in televised interviews on Sunday said funding for the wall is a priority in budget negotiations ahead of a potential government shutdown Friday, but stopped short of saying Trump would not accept a bill that didn't include the funding.