Andrew Constance has called for a recount in the NSW electorate of Gilmore moments before Labor MP Fiona Phillips was due to claim the federal seat.
Ms Phillips is 373 votes votes ahead of the former NSW minister, who ran as the Liberal candidate.
Mr Constance secured a 2.44 per cent swing towards him, bucking the national trend, but ended up just under 0.2 per cent behind the incumbent Labor MP.
Mr Constance has now called for a recount with the official result due to be called at 2pm on Tuesday.
The Australian Electoral Commission has confirmed the postponing of the official declaration to consider the recount request, but didn't put a timeframe on the consideration.
A recount occurs if the margin of votes between candidates listed first and second ends with less than 100 votes after the distribution of preferences.