The coalition is set to pick up three Senate seats in Victoria and South Australia, as counting for the upper house continues following the election.
Of the 76 seats in the Senate, 40 were up for grabs at the May 21 poll.
Based on current projections, the Liberal-Nationals coalition is set to have the most senators in the new parliament, with 33 upper house members.
Labor is set to hold 26 seats when the Senate sits in July, with three new faces in Jana Stewart and Linda White from Victoria and Fatima Payman from Western Australia.
There will be 12 Greens members in the Senate, should the current projections hold, with the party in line to pick up three extra seats.
Based on the current numbers, Labor and the Greens combining for a vote would be able to block proposals from the coalition, but would not be enough to secure a majority on the Senate floor without the help of a crossbench member.
Pauline Hanson is expected to be returned to the Senate for Queensland, giving One Nation two seats.
The Jacqui Lambie Network is also expected to get a second seat, with former Lambie staffer Tammy Tyrrell expected to be elected.
Former Wallabies star turned independent candidate David Pocock is on track to defeat Liberal Zed Seselja in the ACT Senate race, making it the first time the territory has not had a Liberal in the upper house.
Election analyst William Bowe said there were still three seats still in doubt as counting continued.
"Victoria ... could provide either a third seat for Labor or the coalition, or the only seat for the United Australia Party," he said.
"The last seat (in Queensland) is down to Pauline Hanson or a third seat for the coalition.
"South Australia ... could provide a third seat to either Labor or Liberal or a seat for One Nation."
Mr Bowe said despite early enthusiasm for the prospects of Legalise Cannabis Australia taking the last Senate spot in Queensland at the expense of One Nation, hopes for the party had faded.
He said the race for the final seats in Queensland, Victoria and South Australia would be close.
"The outcome of these races will be third seats for the Liberals in Victoria and South Australia and Pauline Hanson will prevail in Queensland," he said.
Should a third coalition candidate get over the line in both states, Greg Mirabella will win for the Liberals in Victoria and Kerryanne Liddle will represent South Australia.
Senator Mirabella, a Wangaratta farmer, filled the vacancy caused by the retirement of Scott Ryan late last year and was considered a long shot at retaining the seat.