Labor MP Warren Snowdon has claimed victory in the Northern Territory seat of Lingiari.
Figures from the Australian Electoral Commission (AEC) show he has an 800 vote lead over Country Liberals candidate Tina MacFarlane.
Less than 200 votes are still to be counted.
The AEC is expected to make an official declaration late today or tomorrow.
Mr Snowdon says it is a narrow victory and highlights the changing demographics in the vast seat, which covers more than 99 per cent of the total area of the Territory.
"I am very thankful for the people of Lingiari for showing their confidence in me by returning me," he said.
Mrs MacFarlane has congratulated Mr Snowdon but not conceded defeat.
She told ABC Local Radio's Kate O'Toole that the national trend towards the Coalition had helped her in some booths but less in more remote areas.
"You can't just expect people to know and start trusting you in a very short period of time," she said.
"You need a long time to earn trust.
"Warren Snowdon has been there a long time and he has been able to establish a relationship with them."