Backers of leadership rival Peter Dutton believe his support levels are quickly climbing and another spill could take place within days.

“Now that the genie is out of the bottle, I’m not sure we can put it back,” Liberal MP Craig Kelly, who backed Dutton, told the ABC.

The prime minister defeated the ex-home affairs minister 48 votes to 35 in a snap leadership ballot on Tuesday before appealing for the party to unify.

“We know that disunity undermines the ability of any government to get its job done,” Turnbull said.

“We’ve got to put 25 million Australians first. They hate it when we are talking about each other.”

Up to nine ministers including four from cabinet offered to stand down after voting against Turnbull, but so far he has only accepted two of their resignations, including that of Dutton.

He also accepted the resignation of International Development Minister Concetta Fierravanti-Wells after she wrote a scathing letter criticising the Liberal party for “drifting too far to the left”.

“I have concerns about the party … we always spoke about the broad church and the importance of balance, this is a concern,” she said after tendering her resignation.

Fierravanti-Wells suggested the prime minister’s support for same-sex marriage had eroded the party’s base and forced angry voters to turn their backs on the Liberals.

Some Liberal MPs believe Dutton’s failed challenge is the beginning of the end of Turnbull’s prime ministership, and that there may be another ballot later this week or when parliament returns next month.

Liberal Tasmanian senator Eric Abetz suggests support for Dutton is growing.

“I think there was a shift after the partyroom meeting with the offers of resignation by a considerable number of ministers,” he said.

Meanwhile, at least three Nationals MPs, including Veterans Affairs Minister Darren Chester, are threatening to quit the Coalition and move to the cross-bench if Dutton, from the Queensland right, becomes prime minister.

“All options are on the table in a volatile environment,” Chester told the ABC.

“There’s no reason why any potential challenger, whoever that may be, should assume that they can command numbers on the floor of the House of Representatives, given we have a one-seat majority.”

Former Nationals leader Barnaby Joyce counselled Chester to remember: “We don’t have a dog in this fight, it’s for the Liberal Party.”

Liberal deputy leader Julie Bishop denied she threatened to quit parliament if Dutton seized the top job, stripping the government of its majority and forcing a by-election.

Bishop also said a number of people who voted against Malcolm Turnbull had since reconsidered their position.

Addressing the media after the spill, Dutton tried to soften his image as a hard-line conservative on social issues and border protection.

He insisted he was a better leader to fight Opposition Leader Bill Shorten at the next election.

“I made a decision to contest this ballot because I want to make sure we can keep Bill Shorten from ever being prime minister of this country,” he told reporters.

He repeatedly refused to rule out a second leadership challenge.

Contributing to Turnbull’s leadership woes are a string of poor public polls and internal anger over his government’s energy and climate change policies.

– AAP