In mid-January, a few weeks before the Iowa caucuses, Senator Bernie
Sanders’s pollster offered a stark prognosis for the campaign: Mr.
Sanders was on track to finish strong in the first three nominating
states, but Joseph R. Biden Jr.’s powerful support from older
African-Americans could make him a resilient foe in South Carolina and
The pollster, Ben Tulchin, in a meeting with campaign aides, recommended a new offensive to influence older black voters, according to three people briefed on his presentation. The data showed two clear vulnerabilities for Mr. Biden: his past support for overhauling Social Security, and his authorship of a punitive criminal justice law in the 1990s.