Former star Labor candidate Maxine McKew says Bennelong voters have a right to expect clarity over their MP's eligibility.
Liberal MP for Bennelong, John Alexander, is seeking advice on whether he is a UK citizen through his British-born father Gilbert Alexander who was born in England in 1907 and arrived in Australia in 1911.
A search of British records found no trace of Gilbert Alexander, who died in 1987, having formally renounced his UK citizenship before his son was born in 1951.
Ms McKew, who unseated then prime minister John Howard in 2007 only to lose the seat to Mr Alexander in 2010, said citizenship was not on the electoral radar seven years ago.
"Had I been more forensic I would certainly have raised questions about section 44 as it pertained to John Alexander," she told AAP on Tuesday.
"But that, as they say, is history.
"The important question now concerns clarity and that is what Bennelong voters have a right to expect."
Ms McKew said voters in 2010 were not prepared to vote for the kind of disaffection and betrayal served up by Labor in removing first-term prime minister Kevin Rudd.
"The Liberals would do well to remember this dramatic change in political fortunes," the now Melbourne-based academic said.
"Bennelong is full of informed voters who pay attention and I suspect they are unimpressed with the present shenanigans in Canberra.
"Labor can certainly mount an effective competitive campaign next time around."
