Michael McCormack will walk into the National Party’s leadership contest on Monday morning as the clear frontrunner to be Australia’s new Deputy Prime Minister.

But while Mr McCormack, member for the New South Wales seat of Riverina, has been touted as Barnaby Joyce’s likely successor, party whip Michelle Landry has reckoned there “will be a few” who vie for the job.

Among the other possible contenders that emerged when Barnaby Joyce fell on his sword on Friday afternoon were Lyne MP David Gillespie and new Agriculture Minister David Littleproud.

The favourite, 53-year-old Mr McCormack is a former newspaper editor who has been in Parliament since 2010 and was promoted to the frontbench as Small Business Minister in 2016.

Now Veterans Affairs Minister, Mr McCormack, who has been referred to as “safe pair of hands”, confirmed he would run for the job on Friday.

“On Monday, I will ask my colleagues to back me for the leadership of The Nationals, so together we can work to grow local economies, increase local opportunities and create local jobs,” he said in a statement.

He had fuelled speculation he was interested in the leadership by repeatedly declining to personally endorse Mr Joyce during a television interview last week.

Victorian Darren Chester, who was dropped from the frontbench by Mr Joyce, and Parkes MP Mark Coulton said they would back Mr McCormack on Friday.

Mr McCormack’s elevation to the Deputy Prime Ministership would cause controversy among LGBTI advocates. In 1993, he wrote a newspaper editorial linking homosexuality and AIDS, saying “a week never goes by anymore that homosexuals and their sordid behaviour don’t become further entrenched in society”.

He has since profusely apologised for the article and voted in favour of same-sex marriage last year.

Assistant Minister for Children and Families David Gillespie, 60, has also been mooted as a possible successor, and confirmed in an interview with 2GB that he would run for the job.

Mr Gillespie, a gastroenterologist, entered Parliament in 2013, winning the seat of Lyne on the New South Wales Mid-North Coast.

Nationals MP David Gillespie is considered an outside chance. Photo: AAP

He is currently facing a challenge to his eligibility to serve in Parliament over a shopping centre he owns that leases space to an Australia Post outlet. He recently offloaded the centre, paving the way for him to run in a byelection.

Though he is considered unlikely to run, Mr Littleproud, 41, has impressed his colleagues as Agriculture Minister after being elevated from the backbench to cabinet by Mr Joyce last year.

Despite his experience, unlike Mr McCormack and Mr Gillespie, Mr Littleproud is already a cabinet minister.

The loyal Joyce ally was an agribusinessman before entering Parliament, and was one of only four MPs to vote against same-sex marriage. A majority of his electorate of Maranoa, in western Queensland, voted ‘No’.

David Littleproud is a close ally of Mr Joyce. Photo: AAP

Mr Joyce would not nominate a preferred successor when asked on Friday afternoon.

Confirming the party would meet on Monday morning to decide its new leader, National Party whip Michelle Landry thought there “will be a few” who run for the job.

“There are a few out there and we’ll have to wait until Monday’s meeting and see and they’ll start ringing around and notify us if they have intentions,” she said on Friday afternoon. 

“What will happen is on Monday after Barnaby’s resigned, we will have a leadership ballot. Whoever the contenders are will have a short speech and then a vote.”

Senators are not constitutionally barred from serving as Deputy Prime Minister or party leader, but the accepted convention is that the position is held by a member of the lower house.