LIBERAL candidate Tony Pasin wore himself out in his bid to fend off Nick Xenophon Team rival James Stacey from claiming the traditionally blue-ribbon seat.
Barker has been held by conservatives for a century and spans the state's south-east corner, stretching from Mount Gambier to the Riverland and Murray Bridge. 
Mr Pasin, who cast his vote yesterday afternoon at Melaleuca Park Primary in Mt Gambier, told The Advertiser he was exhausted.
"I'm feeling tired," Mr Pasin said. "It's been a long campaign. Myself and my volunteers have worked really hard and I'm particularly humbled by the support I have received." The 38-year-old father of two operates a private law firm in Mt Gambier, and has held the seat of Barker since 2013.
But an unexpected rise in popularity of Nick Xenophon Team candidates across the state forced Mr Pasin and his team to strengthen their efforts.
Mr Pasin, who advocated for regional healthcare, jobs, telecommunications, and improvements to roads said it had been hard to gauge the response of the electorate until the votes were in.
Mr Pasin was facing Labor candidate Mat O'Brien, who operates a small fitness business out of Murray Bridge, and Nick Xenophon Team candidate James Stacey, a National Party Senate candidate at the 2013 election.
Mr Stacey, who grew up in the farming community of Langhorne Creek, was focused on the agricultural sector and the prosperity of regional South Australia.
He spent yesterday trying to win over undecided voters in the Barossa Valley. He said winning the seat would be a "long shot" but he hoped Barker would become marginal to make things "interesting".
"I think there is a large proportion of the community who would like to see some change," he said.
BARKER PASIN (LIB) O'BRIEN (ALP) STACEY (NXT)MARGIN 16.6%