The Australian Electoral Commission is considering whether to conduct a recount for the NSW seat of Gilmore, postponing the declaration on the same day Labor MP Fiona Phillips was set to retain the federal seat.
Liberal candidate Andrew Constance wrote a letter to the electoral commissioner requesting the recount.
The commission has confirmed the postponing of the official declaration to consider the recount request, but didn't put a timeframe on the consideration.
Ms Phillips is 373 votes votes ahead of the former NSW minister, who ran as the Liberal candidate.
The official result was due to be called at 2pm on Tuesday.
"As counting has progressed over the last couple of weeks, my scrutineers have raised concerns in relation to certain aspects of the process, particularly the scrutineer of informal votes," Mr Constance said.
"Given the close result, I believe there are strong grounds for a recount and I have submitted a request to the Australian electoral commissioner."
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.
A recount occurs if the margin of votes between candidates listed first and second ends with fewer than 100 votes after the distribution of preferences.
A Liberal win in Gilmore would give Labor a bare minimum majority of 76 seats in the 151-seat parliament.