Wellens, who made almost 100 appearances for Rovers between 2007 and 2009 and helped them win promotion to the Championship, has been training with Paul Dickov's side since having his contract with Leicester cancelled by mutual consent last week.
The 33-year-old midfielder is now a free agent and has a deal on the table from Doncaster but it is subject to the conclusion of successful investment talks currently taking place at the South Yorkshire club.
He told BBC Radio Leicester: "I've been training with my old club Doncaster. I've got a contract offer but it depends on investment coming into the club. If that materialises then great but it hasn't at the moment.
"There are four or five clubs interested and waiting to see what happens."
After being released by Manchester United in 2000 Wellens played for Blackpool and Oldham prior to his arrival at Doncaster.
In 2009 he joined Leicester but made just four appearances for the Foxes last season and was sent to Ipswich on a month-long loan as he recovered from a cruciate ligament injury.