While the about 10,000 postal votes that remained uncounted as of Wednesday night are unlikely to shift results in Fenner and Canberra, the AEC's Evan Ekin-Smyth said the 100-strong staff still had a significant task ahead.

"There is no firm indication to when the seats of Canberra and Fenner will be officially declared," he said.

"The Senate count for the ACT will take longer – likely to be a few weeks."

He blamed "the logistical challenge and sheer volume" of votes for the long process.

Volunteers in Canberra and AEC staff across the country are likely taking extra care after 1375 ballot papers went missing in Western Australia during the 2013 election, forcing the state to go back to the polls.

Mr Ekin-Smyth said many of the 282,126 people enrolled to vote in the territory voted interstate, and "a small number" did so overseas, though he could not provide figures.

With the cut-off for postal votes not until July 14, more may yet arrive.

Wherever Canberrans voted, it seems many took this federal election more seriously than the last, with latest AEC figures showing a drop in informal votes in the ACT from 3.8 per cent down to 2.4 per cent.

Results from formal votes returned Canberra's two lower house representatives Gai Brodtmann and Andrew Leigh with a comfortable majority.

With the Liberals' Zed Seselja on track to be returned and Labor senator Katy Gallagher winning a seat with flying colours, the ACT's Senate representation also looks set to remain unchanged.

As of Wednesday afternoon, Mr Seselja was closely scraping behind the required quota to win a Senate seat.

AEC data also revealed the Greens polled higher than the Liberals on primary votes at eight booths in Fenner, but still behind Labor.

And Canberrans voted Greener but less independent than the rest of Australia, though faced with fewer preference options.