Labor MP Mike Kelly is expected to retire from federal parliament within days, triggering a by-election in the marginal NSW electorate of Eden-Monaro.
Mr Kelly has long battled chronic health problems dating back to his Army service in Iraq and Somalia.
A contest for his seat could be held within months, with NSW deputy premier John Barilaro and Liberal Senator Jim Molan touted as possible candidates.
Earlier this year, Mr Kelly told SBS News he was determined to stay on in politics after a life threatening health scare last October almost forced his exit.
“I’ve always known that you can only continue in a job like this, in a seat this size, if you’ve got good health,” he said.
“I didn’t realise how long it would take to build up strength again and get everything back in order. But I feel I’m over the worst of it.”
ALP sources have suggested former NSW state election candidate Bryce Wilson could be in the running.
Labor MP Mike Kelly in hospital battling renal failure. Source: Supplied
Labor leader Anthony Albanese said Mr Kelly deserved privacy as he dealt with his well-known medical issues.
"That's deserving of respect and deserving of something better than speculation which has been around for the last year also about Mike Kelly," Mr Albanese told ABC radio on Tuesday.
NSW deputy premier John Barilaro has said he would not rule out contesting Mr Kelly's federal seat in the event of a by-election.
This could pose a threat to Nationals Leader Michael McCormack who has already faced one leadership challenge from predecessor Barnaby Joyce on the first sitting day of the parliamentary year.
NSW Deputy Premier John Barilaro. Source: AAP
Liberal Senator Jim Molan, who lives in Eden Monaro, has also said he would keep all his options open.
Liberal frontbencher Greg Hunt said he had great respect for Mr Kelly.
"I have had the pleasure of working with him over the years," Mr Hunt told reporters in Victoria.
"He is a very decent person who served Australia with extraordinary courage and distinction through the military and he served Australia well through his service in parliament.
"Mike, you have served us well. I wish you well, if that is your decision."
The Labor MP was rushed to a hospital for emergency surgery after collapsing in October last year.
Mr Kelly has said his ongoing health problems stemmed from long-term damage to his renal system suffered through severe dehydration during military tours in Somalia, East Timor, Bosnia and Iraq.
