The decision by the Australian Electoral Commission due to the narrow margin between the two main candidates means Liberal Peter Hendy will have to wait until Monday at the earliest to be formally declared the winner of the bellwether seat.

Labor's Mike Kelly has conceded defeat after Labor suffered a swing of almost 5 per cent against it in the electorate.

''Shut down the office today, watched the signs come down, said adieu to the team, drove home in the grey sad rain,'' Dr Kelly tweeted this week.

Mr Hendy has not claimed victory despite maintaining a narrow lead as counting of votes continues.

By Thursday the commission had counted almost 94 per cent of the votes.

Mr Hendy had 50.62 per cent of the vote, on a two-candidate preferred basis, to 49.38 per cent to Dr Kelly.

The commission said 1099 envelopes containing postal or pre-poll votes remained to be counted.

The deadline for receiving postal votes is Friday's mail.

Divisional returning officer for Eden-Monaro Pat Satie said he was receiving a steady stream of mail containing absent and pre-poll votes which had been cast in various parts of Australia.

''The receipt of postal votes closes tomorrow and because of the difference between the two major candidates, my state office has advised that I should wait at least until tomorrow to do the final count,'' he said.

''Then I will apply to state office to hold the declaration of the poll but it won't be tomorrow. My best estimate would be early next week.''

Dr Kelly, the former Minister for Defence Materiel, is being urged to put up his hand for the Senate vacancy expected to be created by the resignation of former foreign minister Bob Carr.

He is being promoted as a ''good fit'' for the Senate where he would be able to debate directly with the new Defence Minister David Johnston.

On Thursday the nominal front runner, union boss Paul Howes, ruled himself out of the position.

''I do not want to be the type of person in this movement who destructs, who divides because of my own personal ambition,'' he said. ''Therefore I think it's in the interest of the movement that someone else takes that spot when it comes up.''

Dr Kelly was unavailable for comment.

He is a former army officer and was the Member for Eden-Monaro for six years.

If he entered the Senate on a casual vacancy, he could set up an electorate office again in Queanbeyan and help Labor's campaigns in Eden-Monaro, Hume and Gilmore.

In that case, he may then decide to leave the Senate at the next election to contest Eden-Monaro again.