"We're negotiating a brief extension. The details still have to be worked out," said the Southampton station's general manager, Wallace Smith.
WLIU put the radio station's license up for sale last August because it was losing more than $1 million each year to run it. A grassroots organization then formed to save the station, offering $850,000 in a bidding process.
By late Tuesday, Long Island University - which owns the license to the station - issued a formal statement that it had granted the grassroots group, Peconic Public Broadcasting, a 72-hour extension to make the remaining payment to the university.
"If payment is not received by that time, the university will begin discussions with several other public radio organizations that have expressed an interest in acquiring WLIU," the statement said.
The radio station had said it was trying to raise the money through donations and a bank loan. It said in a statement Tuesday it had made "significant progress" and would be able to complete the purchase "with additional financial support from the community and continued patience" from the university.
The station is at 88.7 FM.