Populists in Europe, the United States and elsewhere — including, in Australia, Pauline Hanson, a senator who has called for a ban on Muslim immigration — have often relied on this argument to rally frustrated working-class voters who fear Islam or believe they are competing with immigrants for jobs or government resources.
Here in Darwin, a northern outpost closer to Indonesia than it is to Sydney, and across Australia, there is little doubt that Mr. Turnbull is focusing on immigration because his government is at risk of being toppled, by rivals on the right or left.
“Citizenship and immigration policy is being used specifically for political ends,” said Henry Sherrell, a research officer in the Development Policy Center at Australian National University.
Ben Saul, the Challis chair of international law at Sydney Law School, agreed, saying there was no apparent need for the changes. “There is little evidence that the current Australian citizenship processes are being abused or admit the ‘wrong’ kind of citizens,” he said.
Australia has been a quiet example of successful mass immigration, perhaps more so than much of the world realizes. About 27 percent of its population is foreign-born, from more than 200 countries — roughly double the ratio in the United States and in England.
The country already requires new immigrants to have substantial knowledge of English and civics. Its extensive citizenship test can only be taken in English, and it includes questions about freedom of speech and other democratic norms.
Criminal background checks are also required. And immigrants who receive the most common temporary work or study visas must sign a “values statement” that includes principles like: “Australian citizenship is a shared identity, a common bond which unites all Australians while respecting their diversity.”
Kevin Kadirgamar, an immigration lawyer in Darwin and president of the Multicultural Council of the Northern Territory, a nonprofit group that hosts citizenship classes for immigrants, said that if the goal was inclusion and integration, Australia had much to build on. And in his view, Mr. Turnbull’s new proposals run counter to what has made it work.
“Citizenship is a voluntary thing,” said Mr. Kadirgamar, 28, who said he became a citizen in 2005 after arriving with his family from Sri Lanka. “It’s an extra step people take to feel part of the Australian family. And now we’re putting up new barriers to that.”
“I’m bewildered as to how some of these changes, such as the English-language testing requirement and the longer wait for citizenship, align with Australian values,” he said.
Supporters of the shift argued that the new policies would reinforce values like fair treatment of women and children. Mr. Turnbull said that the additional requirements were good for immigrants as well as the country.
“I mean, does anybody doubt that if you want to succeed, if you want to even have a chance of succeeding in Australia, you need to be able to speak English?” he said.
The immigrants most likely to be affected are those who have come on humanitarian visas, since those who arrive with work or study visas already must pass rigorous English tests.
Mr. Do, who was picking up his son Thursday at a school for children with special needs, said his wife was eager to become a citizen because of the peace of mind it afforded her when she visited relatives in rural Vietnam. It is the same peace of mind he feels, having fled political oppression in that country.
“When you have that passport, you feel safe,” said Mr. Do, who said his father was thrown in jail by Vietnam’s Communist government when he was a child. “If something goes wrong, they’ll protect you.”
At the Multicultural Council’s headquarters, just persuading people to prepare for the current citizenship test has been a challenge.
Letty Heartburns, 41, an Australian citizen from Zimbabwe, said the English classes she taught often included refugees from war-torn countries like Congo, people who are eager to belong but limited in their educations. “I had 40 students here one time, and the only thing every one of them could say was ‘Hi,’” she said.
The hurdles often go beyond language, Ms. Heartburns said. “The whole test is on the computer, and they are so scared to just hold the mouse,” she said. “You have to take them and show them that this thing won’t bite you.”
It is unclear how many legal residents are eligible for citizenship but do not apply. Border officials did not respond to a request for those figures.
In the United States, millions of immigrants who could become citizens do not do so, often citing the expense and challenge of the citizenship test. Many immigrants here are said to express similar concerns.
In 2015-16, 102,029 people took the citizenship test, and 3,447 people failed it more than three times, according to the Department of Immigration and Border Protection.
Under the new rules, which must be approved by Parliament, three failures would mean the end of a person’s attempt to become a citizen. Those who are most likely to fail and keep trying, according to the figures: immigrants who reached Australia as refugees.