As counting continued after Saturday's election it appeared the Nationals would hold 16 seats in the House of Representatives, including LNP MPs in Queensland who sit in the Nationals party room in Canberra.

Nationals candidate Anne Webster picked up Mallee, where Andrew Broad retired, and Pat Conaghan replaced Luke Hartsuyker in Cowper.

However, the party took a hit in the Senate.

Tasmania's Steve Martin appears unlikely to hold his Senate seat.

Townsville-based businesswoman Susan McDonald is expected to take over retired senator Barry O'Sullivan's Queensland Senate seat.

And water policy officer Perin Davey is still a shot to take up a NSW Senate seat, vacated by John Williams.

However, if Ms Davey does not win, the Nationals will only have Matt Canavan, Bridget McKenzie and Ms McDonald in the upper house, reducing its current numbers by two.

The Nationals will spend coming weeks discussing a new coalition agreement - a private letter between leader Michael McCormack and Prime Minister Scott Morrison setting out how the coalition will operate and key policy areas.

Nationals strategists say Mr Morrison's visits to regional seats delivered a bump in internal tracking polls.

Labor's so-called "retirees tax" - reforms to franking credits - was considered a key issue in Nationals-held seats.

The issue of Senate numbers could cause friction in the party ahead of parliament sitting.

But it's not expected Mr McCormack will spill the leadership, given the government was returned.

Former Nationals leader Barnaby Joyce said on election night Mr McCormack should be commended for his work in the campaign.

Australian Associated Press