A delighted Mr Woodhouse told the Otago Daily Times he was enjoying a quiet day yesterday, after the "glory" of Saturday.
National received 21,466 party votes in Dunedin North and South, beating Labour's 20,292.
"We're just a little bit pleased with ourselves, today."
There was much yet to analyse in the Dunedin results, including the lower turnout, and special votes could have an impact, Mr Woodhouse said.
It was possible Dunedin, like the West Coast or parts of Auckland, could not be considered safe Labour any more.
"We always knew that there was a time coming where - a tipping point almost - where Dunedin would no longer be seen as a staunchly red city.
"I think we're very close to, if not having already reached that tipping point."
Mr Woodhouse and Dunedin South National candidate Joanne Hayes worked together across Dunedin to promote "brand National", which proved effective.
Labour needed to work on its party vote strategy, both in Dunedin and further afield, he said.
