Invercargill Mayor Nobby Clark is scheduled to undergo heart surgery next week, after suffering a minor heart attack on Wednesday.
Clark was taken to Southland Hospital and stayed overnight as a precaution after the incident on 27 December, the council said.
He was then transferred to Dunedin Hospital for more tests yesterday.
Deputy mayor Tom Campbell said on Thursday that Clark was in good spirits and recovering well.
Clark will stay in Dunedin Hospital with his family until his surgery next week, Campbell said.
Campbell said Clark's recovery was likely to take a couple of months and that he would take the reins at council in the meantime.
The deputy mayor would have the same powers as the mayor, said Campbell.
"The mayor and I have always worked very closely together so council will carry on carrying on," he said.
"There are two major projects that Nobby has been personally driving; one is the building a new museum, and another one is the refurbishment of a place here called Wachner Place, which is almost like a town square, and we will continue to drive that just as hard as Nobby would wish us to."
Campbell said the council had just completed a Long Term Plan, which would go out for public consultation in January, and be finalised in February.
Clark won the mayoralty from long-time incumbent Tim Shadbolt in last year's local body election.