“Immigration is a growing vulnerability for the president,” John Anzalone and his team warned in a package of confidential polling, voter surveys and recommendations compiled for the White House. “Voters do not feel he has a plan to address the situation on the border, and it is starting to take a toll.”

Within a month, there was another stark warning. “Nearly nine in 10 registered voters are also concerned about increasing inflation,” said another memo obtained by The New York Times.

The series of confidential polling data and weekly memos presented to Mr. Biden’s inner circle from April of last year to January of this year provides a road map of the declining support of a president whose initial legislative proposals spurred comparisons to the New Deal or the Great Society.

Despite the early warnings from his pollster, Mr. Biden and his top advisers have struggled to prevent either issue from becoming a major political liability.