WASHINGTON — The Biden administration said Thursday that a new fast-track docket in immigration courts will cut the time it takes to decide asylum claims from years to months for some single adults.

Migrants who settle in five cities — Atlanta, Boston, Chicago, Los Angeles and New York — will be placed in a ''recent arrivals docket'' that aims to have judges rule on their claims within 180 days, instead of the four years or so that it currently takes. The bottlenecked courts are believed to be a significant incentive for more people to come, especially those with weak claims.

The Justice Department has assigned 10 judges to the effort. Authorities said they didn't know how many cases they would handle, making it difficult to assess the potential impact.

Administration officials said the failure of a sweeping Senate bill this year explains the absence of bolder moves, a familiar line of attack against Republicans who have seized on unprecedented border arrivals to fault President Joe Biden's handling of immigration in an election year.

''This administrative step is no substitute for the sweeping and much-needed changes that the bipartisan Senate bill would deliver, but in the absence of Congressional action we will do what we can to most effectively enforce the law and discourage irregular migration,'' said Homeland Security Secretary Alejandro Mayorkas.

Authorities said the five cities were chosen because because judges there had some availability to hear cases and because they were big destinations for migrants.

Asylum seekers are eligible for work permits within six months of arrival, which critics say is an incentive to come even if their claims are weak. The longer they're in the U.S. and have established families or community ties, the more opposition there is to eventually sending them back to their home country.

The administration has tried for years to move more new arrivals to the front of the line for asylum decisions, hoping to deport those whose claims are denied within months instead of years. The Obama and Trump administrations also tried to accelerate some cases on a separate track going back to 2014.

In 2021, the Biden administration introduced a ''dedicated docket'' for asylum-seeking families in 10 cities to be bumped to the head of the line in court and have their cases decided within 300 days. In 2022, the Biden administration introduced a plan to have asylum officers, not immigration judges, decide a limited number of family claims in nine cities.

Dana Leigh Marks, who retired in 2021 after 35 years as an immigration judge, said asylum seekers, even those who can pay, have been unable to hire attorneys under previous ''rocket dockets'' because there wasn't enough time. Marks also said those initiatives failed to slow migration.

''It's a political response because the problem is so enormous and people are concerned, but it's really just a superficial Band-Aid on a gaping wound,'' Marks said. ''It's never worked in the past and there's no reason to think this time would be different.''

A labor representative for immigration judges said he was waiting to learn the scope of the latest effort and how it will affect caseloads but said it had potential to undermine rights to a fair hearing. ''Hopefully the Biden administration learned from past mistakes,'' said Matt Biggs, president of the International Federation of Professional and Technical Engineers.

The immigration court backlog has surged to 3.6 million cases. There are roughly 600 judges in 68 courts. The plan announced Thursday would not include money for more judges.

The announcement came a week after another new policy aimed at a limited number of asylum seekers to reject their claims earlier in the process if they are deemed public safety threats.

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Spagat reported from San Diego.