Deering, who is on the U's transfer list, should be available to face Southport on Saturday if the paperwork is sorted in time.
"It's a chance for Sam to get games," Oxford boss Chris Wilder said.
"We know that Newport will look after him. It's a good opportunity for Sam."
Although Deering remains transfer-listed, Wilder has indicated that the winger could still have a future at Oxford United.