Liberal candidate Andrew Constance wrote a letter to the commission asking for the recount, citing concerns about the scrutineering of informal votes.

"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 said on Tuesday.

Mr Constance lost to Labor incumbent Fiona Phillips by just 373 votes, and said he was "disappointed" by the AEC's decision.

"Naturally, I am disappointed and will review the Commissioner's reasons," he said.

The seat was set to be formally declared on Tuesday but was postponed in light of the recount request.

Mrs Phillips described the last few days as an "emotional roller coaster" but was elated to announce the Gilmore declaration will be held on Thursday.

"The AEC has got a really important job to do to make sure the election is done right," Mrs Phillips said.

"I'm just happy the declaration of the poll will happen again ... so I can just get on with all the work that needs to be done."

An electoral commission spokesman said the request for a recount was carefully considered, with the counting process for Gilmore carried out in line with electoral laws.

"The AEC was sufficiently satisfied the count occurred in line with the Electoral Act, and the checks and rechecks were sufficient to ensure that the result was accurate," the spokesperson said.

The Liberals had a 2.44 per cent swing in the South Coast seat, which bucked the national trend, however, Mr Constance fell 0.2 per cent short.

Mrs Phillips added the race for Gilmore against her opponent was always going to be tight.

"(Andrew Constance) had been a local member for 18 years ... and I think for me to actually come out and win this does say a lot," Mrs Phillips said.

"It's actually making history ... it's the only time a Labor MP has won this seat twice ever.

"It's really thrilling to be now under an Albanese Labor Government and just having that direct contact with the government to support so many people in our area."

A recount in the electorate would have automatically been triggered if there were fewer than 100 votes between first and second placed candidates.

The final result in the House of Representatives is expected to be 77 seats for Labor, 58 for the coalition, four Greens, 10 independents, one Katter's Australian Party MP and one Centre Alliance MP.

- with Australian Associated Press