2.18PM UPDATE: The seat of Indi has gone "maverick", according to the AEC.
With the result hinging on pre-poll and postal votes, it is unlikely voters will know who has won for at least 10 days.
AEC returning officer Jenny Essex said a seat is defined as "maverick" when the results go against the anticipated two-party preferred outcome.
"We'll probably get closer to an indication a week-and-a-half away," Ms Essex said.
"We're waiting for all the postal votes to come in ... we can't say they've all been counted until 13 days post-polling."
AEC spokesman Steve Kennedy said addiitonal scrutineers were being sent up tomorrow morning to help with the count.
1.42PM UPDATE: Reports remain on social media that Mrs Mirabella was asked to remove posters. ALP member and former candidate Zuvele Leschen tweeted: “One of our members approached by AEC official who assumed the banners were ours and ordered their removal.”
A second AEC spokesman Steve Kennedy reaffirmed Ms Essex's statement that Mrs Mirabella was not told to remove posters.
11.58AM UPDATE: Rumours were circulating yesterday that Mrs Mirabella had been ordered to take down some of her anti-independent posters at Wangaratta TAFE, but the AEC returning officer for Indi Jenny Essex said this was not true.
The AEC says there can be no political advertising within six metres of polling booth entrances - Ms Essex said Mrs Mirabella had complied with this.
“The AEC didn’t ask her to take anything down,” she said.
11.21PM UPDATE: Indi will be decided on pre-poll and postal votes, and a result may not be known for days.
As of 11pm, the AEC website showed Sophie Mirabella had 43 per cent of the primary vote, and Cathy McGowan 33 per cent.
But with preferences distributed, the pair are neck-and-neck.
Win or lose, Ms McGowan and her team are treating the result as a victory.
She received a rock-star reception as she arrived at Wangaratta's Performing Arts Centre, the crowd of 300 chanting a defeaning tribute.
"We used to be called a safe seat, but we've changed that," she said, as she addressed the gathering just before 10pm.
"Democracy is alive and well in Indi."
Among the attendees were prominent Nationals identity and former Murray Valley MP Ken Jasper, who called the close results "a wake up call ... for representation to this area."
Ms McGowan thanked Liberal member Sophie Mirabella for her work in the electorate over the past 12 years.
Mrs Mirabella likewise acknowledged Ms McGowan for her efforts and wished her well.
She emerged from her Wangaratta office just after Tony Abbott's victory speech to address a small but loyal band of supporters at Cafe Martini.
She called the evening a "victory for the Coalition" and that Australia had been returned to "a strong and stable government".
She said those who had voted independent in Indi had "had the wool pulled over their eyes" by a Labor-Greens-independent alliance in the electorate.
She thanked her family, staff, and coalition colleagues including Barnaby Joyce, and congratulated her party leader and new prime minister Tony Abbott.
This is our final post for tonight. Don't forget to check back tomorrow for more online coverage and a full election wrap in Monday's Border Mail.
9.33PM UPDATE: Independent candidate Cathy McGowan has arrived in Wangaratta with the seat of Indi resting on a knife edge.
The final result may not be know tonight with the seat held by Sophie Mirabella since 2001 likely to come down to preferences.
Ms McGowan was part of a 250-strong crowd at The Cube in Wodonga tonight before hitting the road for Wangaratta where Mrs Mirabella has shunned media to date.
With nearly half the votes counted, Mrs Mirabella has 43.67 per cent of the vote compared to Ms McGowan's 32.91 per cent.
Ms McGowan has had strong support across the electorate and is claiming victory in places such as Mitta, Whitfield, Chiltern, Beechworth and Yackandandah.
She is also polling strongly in the big population centres of Wangaratta and Wodonga.
"It is going to be very close," she said.
" I am getting more optimistic. But it is too early. There is a really good feeling here.
"We've done what we set out to achieve, make the seat really close and brought the community with us."
In Farrer, sitting member Sussan Ley is heading for a comfortable win.
INTERACTIVE: Click here for the latest results in our electorate-by-electorate map.
8.26PM UPDATE: Cathy McGowan and her supporters say they're thrilled with the results so far.
With 35 per cent of the primary vote counted so far, Liberal incumbent Sophie Mirabella is on 44 per cent while Ms McGowan has 31 per cent.
It's looking increasingly likely the result won't be known tonight.
About 300 supporters are gathered at Wangaratta Performing Arts Centre watching the tally come in, with another 150 at The Cube in Wodonga.
Ms McGowan said all eyes were glued to the big screen.
"It's neck-and-neck," she said.
Her media advisor Cambell Klose said the atmosphere in Wangaratta was "festive".
"Everyone's really proud of what we've done," he said.
7.54PM UPDATE: Indi looks set to be decided on preferences.
Liberal incumbent Sophie Mirabella is claiming 44 per cent of the vote so far, with independent Cathy McGowan on 33 per cent. The ALP's Robyn Walsh is on 10 per cent.
Mrs Mirabella has so far remained in her Wangaratta office, while a small gathering at nearby Cafe Martini watches the results on the big screen.
A spokesman for Mrs Mirabella said media would be notified when she was ready to make a statement.
6.58PM UPDATE: The Indi electorate hasn't seen a race quite like this. But by this afternoon, it was clear the intensity of the campaigns from Sophie Mirabella and Cathy McGowan had taken its toll on voters.
INTERACTIVE: Click here for the latest results in our electorate-by-electorate map.
4.55PM UPDATE: A Sky News/Newspoll exit poll just after 4pm shows the Opposition will win 97 seats, a 25-seat gain, with the Australian Labor Party set to lose 21 seats and have just 51 MPs in parliament.
The two-party preferred result, based on marginal seats in NSW and Queensland, gave the Coalition 53 per cent of the vote to Labor's 47 per cent.
Meanwhile, the latest Roy Morgan-Channel 10 exit poll has a similar look, with the Coalition holding a 52 per cent advantage to the ALP's 48 per cent.
3.50PM UPDATE: Election day for Sophie Mirabella got off to a bumpy start this morning amid accusations the Liberal incumbent had plastered campaign material all over polling booths in Wodonga and Wangaratta.
A spokesman for Mrs Mirabella said accusations of swearing and aggression were “a bald-faced lie”.
He said there was a small “kerfuffle” but that they were clearly working within AEC guidelines.
The spokesman was unaware of Mrs Mirabella being asked to take down any of the signs despite pictures on social media of Mrs Mirabella and husband Greg pulling posters down in Wangaratta this morning.
2.39PM UPDATE: Voters have turned out in droves at polling stations across regional Australia, as the final hours of the 2013 federal election tick away. Take a look back at the campaign from the major parties in our online mega gallery.
Meanwhile, if you've even thought about donkey voting as a form of protest, here's some good reasons not to.
1.28PM UPDATE: The latest Age/Nielsen survey suggests 54 per cent of the nation's 14.7 million electors are embracing the Coalition. Labor's primary vote has slumped to 33 per cent, with the Coalition on 46 per cent.
A Roy Morgan-Channel 10 exit poll also has the Coalition winning comfortably with the primary vote at 42%, Labor with 34.5% and the Greens at 11%.
Not sure which channel to keep up with all your election coverage? Here's a rundown of what each broadcaster is providing tonight.
12.15PM UPDATE: There's been allegations Liberal supporters have wallpapered polling booths overnight in Wangaratta and Wodonga. Several people have tweeted pictures puporting to be Sophie Mirabella and her husband removing the posters, allegedly at the behest of the AEC. Check our Storify feed below.
10.50AM: Welcome to our election day coverage! We'll be updating at regular intervals throughout the day as the battle for Indi reaches its reckoning.
Incumbent Sophie Mirabella faces the fight of her political life to hold on to the traditionally blue-ribbon Liberal seat, with independent Cathy McGowan running a well-resourced campaign that has captured the voting public's imagination.
Meanwhile, over the border in Farrer, Sussan Ley is expected to increase her winning margin.