The US is scrapping the document used by immigrants to apply for American citizenship, replacing it with a more complex form that includes questions about the applicant's links to terrorist groups, genocide, militias, prisons and military training.
Immigration officials said the changes were made partly to comply with new US laws aimed at combating terrorism and child soldiers, and partly to make the form easier to process.
Although it is now 21 pages long instead of 10, the officials noted that considerable space was taken up by thick bar codes on every page.
But some organisations that help US green-card holders apply for citizenship say the changes will intimidate people into not applying, especially those with limited English who might have difficulty understanding the new questions. Some are long and complex, with numerous technical terms.
"At a time when we are all trying to naturalise as many people as possible, this will be a lot more laborious, time-consuming and discouraging for some people to fill out," said Eric Cohen, executive director of the Immigrant Legal Resource Centre in San Francisco.
His group had suggested wording some questions more clearly but immigration officials had ignored it.
"We are concerned that the new form will impact the vulnerable populations we serve," said Jean Atkinson, of the Catholic Legal Immigration Network, which helps more than 10,000 low-income legal immigrants become citizens each year.
"It's safe to say the level of English it requires is significantly higher than the level required to pass the citizenship test."
Since 2008, a yearly average of 750,000 green-card holders have become naturalised citizens. About 100,000 a year come from Mexico.
Other countries of origin with more than 20,000 immigrants who become citizens each year are China, India, the Philippines, El Salvador, Cuba and Vietnam.
Very few naturalised citizens come from countries associated with terrorism or child soldiers, but the Intelligence Reform and Terrorism Prevention Act of 2004 and the Child Soldier Prevention Act of 2007 require that US officials "obtain sufficient evidence" to decide whether every foreign-born person in the US may be barred from permanently immigrating.
The Obama administration, while increasing border-protection efforts and deporting record numbers of illegal immigrants, has been working to streamline and speed up the process of residency and citizenship for legal immigrants.
Officials claim that the new application form would be easier and faster for them to process, and that none of the rules for eligibility had changed.
Immigration officials have given prospective citizens 90 days to apply using the current forms.