SYDNEY, Australia — Scott Morrison, Australia’s conservative prime minister, scored a surprise victory in federal elections on Saturday, propelled by a populist wave — the “quiet Australians,” he termed it — resembling the force that has upended politics in the United States, Britain and beyond.
The win stunned Australian election analysts — polls had pointed to a loss for Mr. Morrison’s coalition for months. But in the end, the prime minister confounded expectations suggesting that the country was ready for a change in course after six years of tumultuous leadership under the conservative political coalition.
“I have always believed in miracles,” Mr. Morrison said at his victory party in Sydney, adding, “Tonight is about every single Australian who depends on their government to put them first. And that is exactly what we are going to do.”
The election had presented Australia, a vital American ally in the Asia-Pacific, with a crucial question: Would it remain on a rightward path and stick with a political coalition that promised economic stability, jobs and cuts to immigration or choose greater action on climate change and income inequality?
By granting Mr. Morrison his first full term, Australians signaled their reluctance to bet on a new leader, choosing to stay the course with a hardworking rugby lover at a time when the economy has not suffered a recession in nearly 28 years.
“Australians are just deeply conservative — wherever possible, we cling to the status quo,” said Jill Sheppard, a lecturer in politics at the Australian National University. “While we want progress on certain issues, we don’t like major upheavals.”
The triumph by Mr. Morrison, an evangelical Christian who has expressed admiration for President Trump, comes at a time of rising tension in the Asia-Pacific region. A trade war between the United States and China has forced longtime American allies like Australia to weigh security ties with Washington against trade ties with Beijing.
Judd Deere, White House deputy press secretary, said Mr. Trump had called to congratulate Mr. Morrison.
“The two leaders reaffirmed the critical importance of the longstanding alliance and friendship between the United States and Australia, and they pledged to continue their close cooperation on shared priorities,” Mr. Deere said.
The conservative victory also adds Australia to a growing list of countries that have shifted rightward through the politics of grievance, including Brazil, Hungary and Italy. Mr. Morrison’s pitch mixed smiles and scaremongering, warning older voters and rural voters in particular that a government of the left would leave them behind and favor condescending elites.
[Read more about the right’s role in Australian politics.]
The candidate Mr. Morrison defeated, Bill Shorten, the leader of the center-left Labor Party, offered an alternative path for Australia: a return to more government intervention on climate change and the economy, and intensified skepticism about the United States and Mr. Trump.
Mr. Shorten, despite being the face of the political opposition for six years, was not an easy sell to voters. His personal approval ratings never matched Mr. Morrison’s, and he relied on the more popular and diverse members of his party to score points with the public.
On Saturday night, he conceded defeat and said he would no longer serve as opposition leader. “I know you’re all hurting,” he told supporters in Melbourne. “And I am, too.”
Mr. Morrison, who kept policy proposals to a minimum during the campaign, rode a singular message to victory: that the Labor Party’s plans to raise spending to bolster public health programs, education and wages would blow up the budget and end Australia’s generation-long run of economic growth.
Ignoring the turmoil that has led his coalition to churn through three prime ministers in six years, he promoted his center-right Liberal Party as a steady hand on the tiller, and made promises of cheaper energy and help for first-time homeowners.
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The intraparty tumult came to a head last year when the Liberals’ right flank ousted Prime Minister Malcolm Turnbull. He was toppled in August after his moderate plan to address carbon emissions was rejected by his coalition’s right wing as going too far.
The party coup soured many Australians on the country’s political system and helped contribute to a degree of voter apathy and anger that colored Saturday’s election.
The campaign was short — just over a month, as is the standard in Australia. And Mr. Morrison’s effort was defined mainly by energy, with folksy events and handshakes for voters, coupled with stiff criticism of Mr. Shorten and a determination not to take no for an answer.
His combative style was especially clear during the second of three televised leadership debates, when he stepped close to Mr. Shorten, who accused him of being a “space invader.”
To those who opposed Mr. Morrison, it was a sign of his bullying tendencies; to those who supported him, it was seen as evidence of passion and conviction.
He portrayed himself “as the good bloke, the good father, the buddy, the mate that Australians would like to have,” said Patrick Dumont, a professor of political science at the Australian National University.
Mr. Morrison, 51, is a veteran politician who has occasionally sought out a provocative role on hot-button issues.
He entered Parliament in 2007, representing a suburb of Sydney. As immigration minister in 2013, he proudly embraced a “stop the boats” policy that denied asylum seekers arriving by sea the right to apply for settlement in Australia.
Under his predecessor, Mr. Turnbull, he served as treasurer, appearing in Parliament at one point with a lump of coal to deliver a message to those demanding stronger action on climate change.
“Don’t be afraid,” he told lawmakers, without mentioning that the coal had been shellacked to keep his hands from getting dirty. “Don’t be scared.”
Though he has an image as a political brawler, Mr. Morrison has proved adept at the insider politics of Canberra, Australia’s capital. He was a loyal foot soldier under Mr. Turnbull until the party pushed to oust the prime minister, at which point Mr. Morrison successfully offered himself up as an alternative.
In August, he became Australia’s fifth prime minister in five years — a sign of how volatile the country’s politics has been over the past few years.
The fact that he escaped punishment from Australian voters for his actions during the party coup surprised many experts.
“I think we’re just getting used to the politics of the absurd,” said Susan Harris-Rimmer, a law professor at Griffith University in Queensland. “It just seems like it’s been a long time since politics was normal anywhere.”
Mr. Morrison, however, rode a wave of conservative support. The coalition of the Liberal and National Parties maintained seats in closely contested suburbs from Perth to Melbourne, and picked up support across rural areas.
In the northeastern state of Queensland, which stretches from Brisbane to the tropics near the Great Barrier Reef, several Liberal Party candidates won handily. That suggested that in the battle over the proposed Adani coal mine, which would be among the largest in the world if it receives final government approval, voters favored immediate concerns about jobs over the risks of climate change.
The Liberal Party did suffer some setbacks. Tony Abbott, the divisive former prime minister, lost his race in a Sydney suburb, where voters demanded more action on climate change. He was one of several conservatives who had argued that most Australians were not willing to trade immediate needs for more distant global concerns.
“It’s clear that in what might be described as ‘working seats,’ we are doing so much better,” he said in his concession speech. “It’s also clear that in at least some of what might be described as ‘wealthy seats,’ we are doing it tough, and the Green left is doing better.”
Mr. Morrison, who has been cautious on climate change, arguing that current policy is enough, can now claim that his mix of enthusiasm and his appeal to working-class economic stability — focused on “a fair go” for all — is what Australians wanted.
Australian voters ultimately stuck with what they knew, while also tilting toward personality. They rejected policies that would have altered the financial status quo, including efforts to cut back on tax perks for older and wealthier voters, and went along with the more energetic politician.
As Mr. Morrison said at his campaign launch, “When I get determined, I get very determined.”