As a longer-term goal, Mr. Biden’s plan calls for an overhaul of the country’s immigration system, including providing a path to citizenship for people who are in the country illegally. He also wants to allow cities and counties to petition for more visas for immigrants to support economic growth.

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Mr. Biden would set the annual cap on refugees admitted to the United States at 125,000, far more than the limit of 18,000 that the Trump administration has set for the current fiscal year, and above the cap of 110,000 at the end of the Obama administration. His plan calls for doubling the number of immigration judges, court staff members and interpreters in an effort to address the immigration court backlog. He would also end the use of for-profit detention centers.

Despite a push on the left to abolish Immigration and Customs Enforcement, or ICE, Mr. Biden’s plan stops short of seeking that or even outlining any major restructuring of the agency. His plan says his administration would ensure that personnel at ICE, as well as at Customs and Border Protection, “abide by professional standards and are held accountable for inhumane treatment.”

Mr. Biden’s plan does not call for decriminalizing unauthorized border crossings, a move supported by some other Democratic presidential candidates. Asked at a debate in June whether they believed that crossing the border without documentation should be a civil offense instead of a crime, most of the candidates onstage raised their hands. Mr. Biden raised a finger.

The next week, in an interview on CNN, he said he did not support the decriminalization of such crossings. “I think people should have to get in line, but if people are coming because they’re actually seeking asylum, they should have a chance to make their case,” he said.

Frank Sharry, the executive director of America’s Voice, an immigrant advocacy group, said Mr. Biden’s plan “can hold up in a rough-and-tumble primary” as well as in a general election.

“The challenge is to adopt an approach that speaks to both progressives and moderates,” he said. “That’s hard to do in today’s Democratic Party. I don’t think most of the candidates get that balance right on most things. But I will give Joe Biden’s team credit for getting it right on this immigration platform.”