Scott Morrison has promised to govern with humility and compassion as coalition MPs and senators come together for their first post-election meeting.

The prime minister welcomed a host of new Liberal and National colleagues to Canberra on Tuesday.

Mr Morrison insisted his “hungry, committed and united” team would focus on the aspirations of ordinary Australians during their third term in power.

“They are the reason we have the opportunity and the great privilege to serve them each and every day,” he told colleagues at Parliament House.

“As I said just before the election, we must burn for the Australian people every single day that we have this privilege of serving them, in this party room and as a government.”

The prime minister promised to do the little things well over the next three years while focusing on maintaining a strong economy.

“This was a key issue at this election,” Mr Morrison said.

“I think we were able, very much, to convey that without a strong economy than all else is in vain.”

While the prime minister was greeted like a rock star, his deputy Michael McCormack was bracing for a pricklier reception when the Nationals met separately.

Some Nationals are miffed the party failed to pick up an extra portfolio in a ministerial reshuffle, and demanded an explanation as to why the agriculture and water resources portfolios were split.

There were expectations the Nationals could receive an extra portfolio such as trade, but its number of cabinet spots slipped from five to four after the Liberals boosted their numbers in parliament.

“Well, there’s always people that are winners and losers and I’m sure for each of them there’s disappointment, and joy for others,” Nationals backbencher Keith Pitt told reporters.

“Anyway, that’s a decision for the leader.”

Mr McCormack shot down disgruntled colleagues, saying the ministry’s composition was a simple matter of arithmetic.

The new ministry will be sworn in on Wednesday before cabinet meets for the first time.

There are several changes to Mr Morrison’s line up.

Melissa Price has been dumped as environment minister, with Sussan Ley taking her place while Energy Minister Angus Taylor adds carbon emission reductions to his responsibilities.

Key Wyatt will become the first indigenous Australian to be indigenous affairs minister, and Nationals deputy leader Bridget McKenzie will be Australia’s first female agriculture minister.

Her colleague David Littleproud – the former agriculture minister – has been given oversight of water resources, natural disasters and emergency management.

Stuart Robert has been promoted to cabinet as government services minister and will oversee the National Disability Insurance Scheme.

Alex Hawke will be international development minister while Richard Colbeck will take on aged care, youth and sport.

Liberal senator Mitch Fifield is off to the United Nations as Australia’s ambassador, with Victorian colleagues including Sarah Henderson jockeying for his spot.

NSW senator Arthur Sinodinos will replace Joe Hockey as ambassador to the US later this year, with Liberal Jim Molan among a wide field wanting to take his seat.