The 44-year-old, who managed Celtic for four years until 2014, is also a free agent after leaving Bolton Wanderers in March and said he was would be interested in speaking to the club’s board.
Republic of Ireland assistant manager Roy Keane, who had a brief spell with Celtic as a player, has refused talk about the summer vacancy specifically but has told newspapers he would like to be a manager again in his own right in the short rather than long-term.
The 44-year-old said in his autobiography that he was offered the Celtic job after Lennon left and before Deila was appointed.
Former Celtic defender Alan Stubbs is hoping to finish the season on a high after his Hibernian side reached the Scottish Cup final and remain in the hunt for promotion from the Scottish Championship.
Asked about the Celtic job, the 44-year-old said: “I don’t think it’s a relevant question to be honest to be asking right now.
“I am more inclined to answer the question by saying that I’m just really sorry for Ronny. He seems a really good guy. I have spoken to him on a few occasions.
“I am disappointed for him more than anything and that is all I will say on the matter because I think you have to show a bit of respect.
“I have got a lot of things to think about between now and 24 May that are going to keep my mind occupied.”
Candidates also being touted by bookmakers are former Liverpool manager Brendan Rodgers and Northern Ireland manager Michael O’Neill.
As are two more former Celtic players – Malky Mackay, who was sacked by Wigan Athletic in April, and Blackburn Rovers manager Paul Lambert.