David Littleproud has quit as leader of the Nationals, admitting that he is “buggered” and needs a break, with senator Matt Canavan saying he would run for the party’s top job in a meeting expected later this week.

Littleproud’s announcement appeared to catch many of his party room colleagues off-guard, with several describing it as a shock or a surprise. Senator Bridget McKenzie didn’t rule out running for the leadership, while former leader Michael McCormack and current deputy leader Kevin Hogan are seen as other potential leadership aspirants. The party is at a critical juncture as it faces a resurgent One Nation which is outpolling the Nationals in many rural and regional areas.

Littleproud was joined by his wife, Amelia, as he made the announcement after question time on Tuesday afternoon. He said he had notified the prime minister, Anthony Albanese, and Liberal leader Angus Taylor ahead of the announcement, but numerous Nationals MPs said they were not aware of the news before Littleproud’s press conference.

First elected to parliament in 2016, Littleproud is a former agriculture and water resources minister, and has led the Nationals since May 2022. He has staved off leadership agitations and formal challenges from party rivals several times, including a long-running disagreement with Barnaby Joyce, which the former Nationals MP blamed as one of his reasons for quitting to join One Nation.

Littleproud said he intended to stay on in politics, plans to recontest his Queensland seat of Maranoa at the next election, and did not rule out serving in a shadow ministry under the next Nationals leader.

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“I’m happy to serve in whatever capacity, but I haven’t got the energy to lead,” he said.

“I’m buggered and I’ve had enough. To lead this great party would be the wrong thing for me to do. I love the National Party. I grew up in it, I’ll bleed, to the day I die, green and gold, I love it, and it’d be wrong for me to say that I’m the right person to continue to lead. That’s tough for me to say, [that] I think someone better can do it, because I don’t have the energy. I’m out of my feet. I’m done.”

Littleproud has led the party through a rocky nine months since last year’s election, twice splitting with the Liberal party and helping to scuttle Sussan Ley’s brief tenure as the leader of the opposition.

His main rival for the party’s top job, former leader Joyce, defected to One Nation in December. Littleproud survived a challenge from fellow Nationals MP Colin Boyce earlier this year.

The Nationals have seen the loss of several other members under Littleproud’s leadership, including Andrew Gee to the crossbench and Jacinta Nampijinpa Price to the Liberals, as well as the loss of Perin Davey’s Senate seat.

The regional party is also facing an existential threat from One Nation, as Pauline Hanson’s party siphons Nationals supporters and members. Littleproud said the Nationals would be able to weather the One Nation threat, but conceded last week that his party could run last in the upcoming Farrer byelection.

Joyce told Guardian Australia that Littleproud has to “take responsibility for the existential crisis he left the party in”.

“If he is ‘buggered’ now then why was that not the feeling he had when the Liberals changed leader? Surely he should have stood down then instead of dragging the Coalition back to the land of chaos,” Joyce said.

The Nationals are expected to hold a leadership election before the end of the week.

Canavan praised Littleproud’s service, and said he would run for Nationals’ leader.

“I believe I have the best chance to help win the battle for an Australia first plan that can deliver a better life for all Australians. I will put my case to my Nationals colleagues in the coming days and will respect whatever decision they make,” he wrote on social media.

Nationals MP Pat Conaghan called Littleproud’s decision a “surprise, while senator Ross Cadell told Sky News he was “shocked”. Cadell said the pair were at a local Canberra pub on Monday night, and that Littleproud hadn’t mentioned anything about his impending news.

“I’m told he hadn’t even decided last night, he had a conversation with his wife last night, and when he woke up feeling better about it,” Cadell said.

Littleproud said he was proud of his tenure leading the Nationals, noting the regional party’s influence in seeing the Liberals adopt policies including opposing the Indigenous voice to parliament referendum, backflipping on a net zero emissions by 2050 commitment, and support for nuclear energy. He claimed he’d had more influence than any Nationals leader since “Black” Jack McEwen, the party’s most storied leader, who briefly served as prime minister after Harold Holt’s death.

Pointing to the defections under Littleproud’s watch, Joyce said: “He most certainly was not Black Jack McEwen.”

Albanese said Littleproud had alerted him to the decision earlier on Tuesday.

“David and I come from very different political traditions and backgrounds, but we share a mutual respect for the great honour of serving in the parliament of Australia and have been able to work together on many issues affecting his community, the regions and our national interest,” Albanese said.

“I wish him well and I am sure he will continue to make a contribution on the backbench in the service of his regional Queensland electorate.”

The opposition leader, Angus Taylor, paid tribute to Littleproud, citing his policy contributions on the Indigenous voice to parliament and nuclear power.

“David has made a great contribution as the leader of the [National] party since 2022,” Taylor said.

“As a wise person said … many years ago: ‘It’s not how you get on the horse that people remember, but how you get off’.

“David is an incredibly committed person when it comes to rural and regional Australia. I have seen time and time again he has stood up for his constituents.”